You are very welcome! Thanks for the thanks; it's nice to know that I could help.
If you are planning to apply to schools with an average score higher than 690, then I would take it again and I would keep your score even if you don't score any higher (or if you do worse!). (If I were you, I'd also ask some admissions consultants what they think, as this is not so much my area of expertise. Post in our Ask An Admissions Consultant folder, if you haven't already.)
690 is a great score, but it's still below average for these schools, so you want to show them that you really tried. They let people in with 690s, so that by itself is not a deal-breaker. But they want to know that you will work hard in b-school / in general to get what you want. So it
could be a deal-breaker if you don't show them that you want to go to their school so badly that you tried hard to hit their average. Trying once does not equal trying hard.
We've had multiple reports this past year of people not getting in off of the wait-list and being told that
one factor was that they scored close to but under the average and didn't try again. We've also had at least two reports of someone reinstating a canceled score after hearing this (to show that they *did* actually try again) and later being accepted off of the wait-list. In both cases the canceled scores were at or lower than the original "kept" score—so the score itself didn't matter.
This is all anecdotal, but we've been hearing it from enough sources now that we think there's a real trend.
You have a great GPA and a solid GMAT score, so the pressure is no longer huge. You can focus on apps and make the GMAT just your secondary concern. If you can eke out another 10 or 20 points, great. If not, you will have tried—and they will know it (ie, keep your score even if it's lower).
Congratulations on your 690, by the way! Let us know how things go!