I'd advise to really try to take the test once if you can. It's a stressful process to prepare for it and it's pretty expensive. You should walk into the test thinking you've studied your hardest and ready to give it your all. If not, it's cheaper and easier to reschedule your exam take it when you're ready vs. retake the test.
Of course, there are many people who retake the exam, so it's not the end of the world if you need to retake it. I know people in my class who retook the exam, and everyone knows sometimes things just don't go right. You just have to learn from your experience and figure out what to do different next time to prepare better.