I think you are on the right track there Nadeem, I remembered I too reached a plateau for my first 4 mock exams (average 55%). From that point I discovered that I failed to integrate all the knowledge areas before, and decided re-read the PMBOK/Rita books again, finally I was able to reach the 70-75% level for mock # 5-8.
In essence:
-Spend your time doing a lot of mock exams
-and more importantly, understand why you answered the questions incorrectly, and fill that gap
-Never rush things, it gives you unnecessary stress, reschedule the exam date if needed
-Make sure you can focus 100% when you are studying and writing the mocks
Good luck, you can do it.