Have you talked to your LSAT instructor? Most of those programs have free tutoring, and this can help you pinpoint what you’re doing wrong. Timed drills are essential, as budgeting your time is nearly as important as knowing how to get the right answer. But your needs may be different, I cannot tell without looking at diagnostic test results.

FYI, The Princeton Review has a sit-down with students who score below 140, explaining that it is rare for students to go up over 10 points, and very hard to get into law school without at least a 150. I don’t know why Kaplan did not do this, but unless there is something unique that you are doing wrong, you might want to reconsider this path.