Quote:
Would you reccomend taking the test a 4th time to get a higher score (645+)
Well that would depend on whether you did anything significantly different between your earlier 3 attempts. Because the GMAT is the kind of test on which, unless you make some changes to your prep, you will end up with the same (or similar) score every time.
Moreover, and you will like the sound of this, if you were to make those changes to your prep, the score can easily jump 50 or more points from here. The standard deviation of the GMAT score itself is about 25-30 points.
Trying the GRE, as others have suggested, is also a very good suggestion. You can certainly consider that.