Well first of all is that a 680 is a pretty good score. The big question is: is it worthwhile to retake? And the answer is: if you have been mock scoring 30 or more points higher, YES! The difference between a 680 and a 710 is BIG (much bigger than the difference between 710 and 740), and you have the time so do it.
Buuut, even if you DON'T get higher, I feel you still can apply to the schools you listed (it will only be a bit harder). You work in an industry that is not all that common amongst MBA applicants, and I feel you can use that to your advantage to tell a unique and compelling story. Plus your excellent GPA will cover any doubts about you from an academic/intellectual perspective.
Hope this helps,
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