I re-took the test and redid AAMC practice tests. I think it was hugely helpful in getting the score I did.
Here's how I feel about retaking tests:
1. There will be mad score inflation. This will not be your actual score, so don't entertain even the slightest hope.
2. I wanted to play the guessing game of how much my score had improved. Okay, I know I wouldn't actually get score [X]....but maybe I'll get X-5? X-3? In the end, it's impossible to tell. Don't waste your time trying to guess. The tests lose all predictive power.
3. So you're not worrying about the score....all you're worrying about is understanding how the MCAT works. It's a standardized test meaning it's....standardized.

Meaning that they use the same kinds of reasoning over and over, that you will need to answer questions right. All you're doing by redoing practice tests is getting that kind of reasoning/thinking skills ingrained in your head. You're getting used to how the MCAT asks questions on subjects; you're getting used to how they take basic science concepts and tests on them.
4. Redoing verbal section is the only one that was not terribly helpful because I remembered it too well.
5. You've taken them before, and it's a practice test. It'll be easy to not treat them like the real thing, to take them lightly. Do your best not to feel like that.
That's about it. I personally attest to retaking tests--your mileage may vary. But those are my thoughts.