750 on practice test, should I expedite study schedule?

If you can get a 750 on GMATPrep, you can get a 750 on the real thing. There's a bit of luck involved in scoring, so with two GMATPrep scores, you'll get a better idea of your true level right now. But even just based on the one score, you'd almost certainly score 720+ if you took the test tomorrow, assuming you perform normally under test conditions, and your most likely score is a 750.

So it depends on your target, but if you'd be happy with a 720, I don't think there's any reason to do any more prep - you could just take the test tomorrow. If you want a higher score, then you might take one other GMATPrep, and if you get a 750 again, then you can be quite confident of getting a 740+ on test day. If you really want to get into the 760+ range (which very few people besides GMAT instructors need to do!), then while you could do that on a good day right now, you'd probably want to make some genuine improvement to get there more consistently. Your Verbal score is outstanding, and in my experience, once you get into the 99th percentile in Verbal, it's very difficult to improve further. But you can very likely improve your Quant score. In fact, I think all of my students who have achieved 99th percentile Verbal scores have been able to score at least a Q49 on the real test - to do that well in Verbal, you really need exceptional logical ability, and that translates well to the Quant section if you learn the material the right way. So that's where you'd do best to focus your study, if you do any more study.

But I agree with bb - you might do one more realistic practice test just to be sure you're comfortable with test taking, but it sounds like you're ready to take the test now, unless you have a very high target score.