I used webmaster's Fetch as Google tool to see how my website looks on Google. The snapshot of rendered page returned by Google is exactly same as my website so I submitted it for indexing.
Logically Google's cached copy of this URL should have been updated by Google but it didn't change and now it's been almost 6 months since the last change. Here is URL for cached copy of this above Page:
It is not happening with all pages. A few pages are being cached properly. Just to give you an idea, this URL is cached properly:
What is the cause of the problem and how to solve it?