I went from 660 to 620 on my second GMAT attempt , although I was scoring in the 700's on practice.
GMAT scores are within +/- 30 pts of ur actual ability. Your current scores are within a range of 40 points (610-570). Now if your schools median GMAT score is within your current range , it shouldnt be a reason to panic.
There is a high degree of correlation between practice tests and the actual test, as long as your not repeating the same tests again. Getting repeated questions which you have mastered creates a false sense of security, and doesnt help build skills. Although its a good thing to do if your a nervous wreck and need additional confidence before the actual test. So if you score a 750, on a test youve done before and need to feel great before your actual test, Go for it! . Again testing yourself on the same concept over and over again doesnt do any good. Instead just work on your weaknesses, instead of just doing multiple tests. I did the same thing the first two times. Didnt work for me.
Finally if you feel underconfident , take up Prep coaching, if you have the time and the money. Your deadlines pretty soon , so dont beleive you can do that unless you decide to postpone/retake ur test.
I knew Im not putting my efforts in the right direction, as my practice test scores were not reflected on the actual test, the first two times , and I didnt also didnt know what was going wrong.
And taking prep coaching worked for me because all I did this time was worked on my weaknesses. I joined Knewton, which and my score went up to 720 after prep coaching, the third time.