Yes, there is some chance that you might have hit 700 with better time management.
First, the schools really do look at your highest score, so no, there is nothing to worry about when re-taking the test.
A 690 is still an excellent score, so whether you take it again depends upon two things:
(1) What are the averages at your desired schools? If a 690 is below average and you think you can get to the average, then it's worth trying again.
(2) How do you feel about it personally? Do you feel like you want to make the effort to go for another 20 points or so as a personal goal? Or are you fine witha 690?
Next, clearly you have a time management issue to be worked out. :) There may be other issues as well.
First, read these two articles:
https://www.manhattangmat.com/blog/inde ... lly-tests/http://www.manhattangmat.com/blog/index ... -the-gmat/Think about how what you've been doing does and doesn't match up with that and how you may need to change your approach accordingly.
Then, use the below to analyze your most recent MGMAT CATs (this should take you a minimum of 1 hour):
http://tinyurl.com/analyzeyourcatsBased on all of that, figure out your strengths and weaknesses as well as any ideas you have for what you think you should do. Then come back here and tell us; we'll tell you whether we agree and advise you further. (Note: do share an analysis with us, not just the raw data. Part of getting better is developing your ability to analyze your results - figure out what they mean and what you think you should do about them!)