You're going to have a very tough time (read: your chances are slim) getting into any top school simply because you already have an MBA.
I wouldn't retake the GMAT - because it's not really about your GMAT beyond a 700.
All you can do at this point is to focus on doing the best job you can on the written applications and interviews (if you get one).
As for schools, even without an MBA, I'd say that schools in the bottom half of the top 16 are more in range (Duke/Darden/Michigan/etc) and schools in the top 8 are stretches to long shots.
To be honest, if you're looking to jumpstart or change your career path, you will have to look at other options (i.e. don't place all your hopes on getting a second MBA as the sole path for getting to your goals, whatever they may be).
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