Hi Sourabh,
I had trouble with the Initiating and Closing process groups as well. I simply underestimated these areas in the beginning because I thought they don't have as many page counts as the other process groups, I was wrong.
1)Seems like you need to work on the Initiating/Closing groups first. I'd start by reviewing those chapter in the PMBOK again, if you have other books/webinars I'd reread them as well.
2)After that review the PMP Exam Outline, understand the concept of each individual step, try to memorize the order as well.
3)Do a mock exam targeting these 2 areas. I personally used Prepcast Exam Simulator because it allows me to filter only the process groups I want.
4)Review the answers that you got wrong, and understand why you got them wrong. After that close your knowledge gap by revisiting the concept in the books or do a search on google.
5)When your knowledge of Init/Close is on par with the rest of the process groups. Repeat 3)-5) but this time do the full 200-question mock.
Best of luck to you on your second attempt, cheers!
-Joe