How can I keep a continuous traffic to my blog even when I am not posting?

If you are not willing to engage with paid adds, then you should start discussion around your blog on social media.

Its really tough to engage audience especially when you are not active on your blog. You need to post an article in your blog once in a week or do something really interesting like uploading infograhics or vblog means video blogging.

Without posting information and updating content, it is not possible to keep continuous traffic according to my observation. 

I agree with the other answers here - content is king.  You can also do paid advertising, even on a very low level.  SEO helps tremendously so you can try to improve that.  And using social media to bring people back to your blog.  Also maybe re-posting archived stories that may be relevant again.