Agreed, with that score you should be safe at 750 and have no need to retake again. Hard to move up from that.
As others have said, subject test scores do not matter that much for college applications. Especially for co21, subject tests might be optional/not accepted at schools that previously required them (MIT). Focus on physics and/or biology instead of retaking math 2, but it doesn’t hurt to retake math 2 if you’re taking three tests on testing day and there’s one spot open.