Do you think there is another way to increase oil price apart from cutting the production which OPEC & NON-OPEC producing nations haven't agreed yet?

Thank you for your invite. Oil prices are not governed by the efficiency of production units. It is managed by the worlds highest consumers such as USA, Europe etc. The present oil prices are victim of world politics that is cold war between USA and Russia principally, so cutting production will not help at this time rather it will effect the profitability of refineries and oil companies and adversely effect the entire Middle East Economy. The solution to raise Oil prices does not lie with OPEC, as the lower prices are due to compulsion to fight competition with USA having reduced their oil prices to slow down growth of Russia and East Europe who principal revenue comes out of oil sales.This is my personnel understanding of world politics and reason of slump in Oil prices. We have to wait till USA production costs go high and their competitive prices start effecting their exchequer. Please be sure the present situation will not last for ever but the damage it has already done will have its effect on development  of new projects in middle east, the loss of profits from oil will reduce employment opportunities in middle east as well as will effect their quality of lifestyle in the coming 2-3 years. Please note my understanding can be absolutely wrong but as you posted your question to me I am presenting my opinion.

I am not a business expert but it doesn't seem possible. The countries can only agree to sell the oil at a higher rate when they agree upon the quota for different countries. If it's a race about who can sell more oil at whatever price, the prices are not going to move up.

Many industry seniors from the world's leading 'oil trading companies' have attempted to draw a close on nearly two years of falling oil prices as Brent Crude rises to its highest level in 2016 so far.With the likes of Vitol, Trafigura, Mercuria, Gunvor, Novum Energy, Glencore and Castleton, who collectively trades more than a fifth of the global oil demand - these companies were almost unanimous in publically announcing that oil prices were unlikely to revisit prices below $30 per barrel experienced back in January 2016.Brent Crude, which is considered the world's benchmark for oil pricing has climbed nearly 4% in April and hit a four month high of almost $45 a barrel with mounting speculation a deal to freeze production at this weekend's OPEC summit is a very likely outcome.Whilst the US market makers reported that oil prices have dropped 1% to $41.70 a barrel having reached $41.83 earlier in the month; it is now reported that oil prices are up 9% month to date.TouchstoneEnergy, the UK's leading IT and Business Systems supplier to the Energy industry commented at their annual customer conference; we need an oil price of at least $60 a barrel if we are to avoid future supply shortages. TouchstoneEnergy also stated that whilst the oil price is rising, it needs to grow much further before any level of confidence will rally big investors.These comments came ahead of meetings planned in Qatar when OPEC and many of the major oil producing nations meet to try to agree an output freeze in a bid to end oversupply.

The main factor affecting oil prices in the international market is Supply & Demand. Demand is purely a market force that no one entity or nation can control. On the other hand, Supply is not just a market force but it's a political decision as well. Since the major reason for the decline in oil prices we've been witnessing over the last two years, and more vividly over the last 6 months, is the over supply of the Saudi oil production with a clear political decision not to cut the supply down, then there is no other factor that can raise the oil price except for Saudi (the main force in the OPEC countries) to decide to slow down it's supply. Not any other single factor can raise oil prices. Some might say but if the US or Russia or Latin America decide to cut their supply this would lead to a natural rise in oil prices. I say this is a theoretical situation but in real life those countries can't afford to cut their oil production down because of their heavy dependency on oil production to support their national demand and also to export to make some revenues. So, it's really up to the Gulf countries, lead by Saudi to make this move because of the huge reserves they have and their powerful control over one of the world's richest oil reserves. 

Thank you for your invite ,Although this question outside of my specialty but I will try to answer from economic side , about your question any country inside organization of opec I think there is No have a choice to sell his oil outside opec price , but in the same time more countries in Opec I think It produces more than its share that cause increase the supply in the market That cause a permanent drop in prices, that mean Within the Organization of Petroleum Exporting Countries does not abide by the laws, addition to that more effects elements prevent to increase the price , strong competition, law of productive countries , political decision , war in the gulf country , the important element more supply sell this product in the black market , From my perspective this is part of the reasons that hinder the increase in oil prices

Regards.

In pure classic economy terms no. Only by reducing the production the prices could bounce back to higher levels.

BUT, there are other elements such as politics, stock exchange market, security contracts etc. that could be used in order to "manipulate" the increment (at least instantly or seasonally) of prices.

yes, not cutting production only, decreasing also by one or more of the biggest producers in world.

The major oil producing countries should meet to resolve the best price for the sale of petroleum products.