Hi Kian_moz
I feel it depends on how you want to change and how big the impact of changing URL as well as title tag. My situation was quite similar to you and I've changed one of my blog post URL and now the page has got 9th position which is much better than before middle of the 2nd page of SERP. But I lost 36 facebook likes, 2 facebook share.
My blog started few month ago and not popular yet so impact was small and now I'm able to get more clicks so changing URL worked fine for me.