Hi Maureen,
Thanks for writing in. GMAT is only one factor in MBA admissions, and since I don't know much else about your application I can't really comment about what the right target score is for you and Kellogg part-time. The median GMAT for that program is a 690, so you will be coming in with a GMAT weakness. If you're confident in your academics and "why MBA?" story, a retake may not be necessary, but you'll need to weigh the rest of your application appropriately.
Good luck!
Daniel Richards
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