Yep, I feel you there. I took the exam in three successive cycles and the exam changed every time. It's the right approach to not just study your supposedly "weak areas". I'd take a close look at how you studied your first and second times, and see if you need to change your study strategy.
Also, doing as many practice problems as you can is a good place to start. When doing practice problems, a few things I found useful to keep in mind were the following:
1. Not look at any answers until I had fully finished a problem, or at least given it my absolute best effort. In my first attempts, I think I'd gotten kind of lazy and would check the answers to questions I thought I didn't know how to do or would get stuck on partway through. This was NOT beneficial to me, at all. I needed to give every question my all before looking at the answer.
2. Related to looking at practice problem answers, I would attack my practice problems like I would if I was actually taking the P.E. Exam. As in, I would go through however many problems (whether it was 5, 20, 40, etc.) I had assigned myself as time allowed, and wouldn't look at the answers for any of them until I was done with all of them.
3. Pay attention to what I did wrong in the problems. Was I making stupid mistakes, like misunderstanding what questions were asking? Was I having trouble converting units? Was I having trouble deciding what information was relevant, and what was irrelevant, to what the question was asking?
In my opinion, it's highly worth it to analyze you study strategy, how you do practice problems, and how you are making mistakes on practice problems. It could give you insight into what sort of traps you might have fallen into in your previous attempts, or at least give you a good idea of what to avoid on your next attempt.
Anyway, take a little breather, enjoy the holidays, and go get 'em in the new year, tiger!