So you're considering retaking the GMAT.
Maybe you weren't satisfied with how you did the first time around, or perhaps your prospective schools have given you some indication that your score isn't quite what it should be.
Before you commit to a redo, consider three questions:
If you prepared thoroughly and did the best you could, you may not see a significant increase in your score. If you didn't spend much time studying, or were surprised or overwhelmed on the day of the test despite your preparation, you can probably improve your score by putting in additional study time.
It may not make sense to spend the time and money to retake the test if you are within the range, even if you're a little below average. You may be better off focusing your efforts on the rest of your application. If the other parts of your application are un-fixable (a poor GPA, for example), then retaking the test will probably be in your best interest.
Be honest with yourself. If you don't have the time or the inclination to prepare, taking the test again probably won't result in a higher score. The exception to this is if you did feel prepared and just had a bad day. Then, by all means, review your material and head back to the testing center.
If you do decide to retake, be sure you've worked out the kinks in your test-taking strategy. And keep in mind that you can only take the GMAT once per calendar month. In addition, you can take the test no more than five times per year—though why anybody would want to take the test five times is completely beyond us. Your three most recent valid (within five years) scores will be reported on your score report.