here's the deal. if you feel that you threw everything you had at the test, then don't take it again. The first time i took that test I took kaplan, and studied, but i didn't go full throttle. I mean where you really lay it all out on the line. I knew that i didn't prepare as i should have. I just sort of studied some, and had a "good idea" of what was going on with the test. But I didn't know it all.
The second time i took it, no kaplan. I had someone to study with, and we were both completely trying to help eachother. It was the best way to study, by far. We knew it all. that's the way you MUST take this test to be happy with yourself.
If you feel like you did all you could, then be happy! you are competitive. Take the test again if you feel that on the first time your didn't know ALL of it. Its the only way to let yourself sleep at night. Best of luck!