Retaking makes sense after only one previous test.
Yes, if you have only taken the SAT I once before, have room at the top above your scores for a highly competitive college (this is the Harvard Forum, after all), then you should definitely retake the SAT I. You may have grown intellectually meanwhile, through further reading and doing math problems, and you will certainly be more familiar with the test the second time around.
My advice would be different for a person who has already taken the SAT I three times, and has higher scores from the earlier tests. (That persons is probably better off building up essays, ECs, or something else in the application, instead of looking obsessed with SAT I test scores.) But your situation is different, and there is very little downside to you taking the SAT I again.
Good luck in your application.