Unless you think you can increase your GMAT by 50 or 60 points, i don't think it's worth it either.
based on your background, I think you'd be competitive. some of it depends on where you did your undergrad (3.5 is great if from a top school; less impressive with a second tier program).
your challenge is that (based on your short submission), there doesn't seem to be anything special or compelling. your career goals are realistic and in-line with your experience, but are they ambitious enough(?). to me, the focus for your app will be strong, compelling, and personal essays that show what makes you tick and what differentiates you from other apps with a similar background to yours.
hope that's helpful,
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