I scored 252 in NMAT this year. Should I appear for a reattempt?

you got a very decent score and mostly you'll get a call for mumbai campus. If you have confidence for getting more than this then take another shot

Look, as long as all your sectional scores are above 75, then you should be completely safe for even Mumbai. Only if one section has a score lower than 70, and you know that you can get it up by 10-15 marks at the the very least, you should give a retake. Otherwise, just wait for a call from NMIMS Mumbai.

sectional scores?