ruturajp,
If you keep taking practice tests and getting the same score range - chances are you keep getting the easy/medium questions right and not getting all the difficult ones right. A few strategies:
1) Answer the easy/medium questions faster, more efficiently and with more confidence so you have more time to attack the difficult questions
2) Learn the tricks you need to answer the difficult ones, avoid the common traps. And really change how you approach the question. If you're approaching from a certain angle, there is certainly someone else who is approaching it differently and getting the answer faster with less headache. Learn that approach.
Take the practice test questions, mix them up in random order, answer them. You should be able to switch from different question types quickly and tweak your attack strategies right away. In the few wks before the exam, really try to focus on answering questions as quickly and efficiently as possible.