I don't know if this is the right forum so please move mods if appropriate.

I have a refundable flight that I charged to my SPG Amex a couple of months ago. I need to refund it and book a new one. Can I just book the new one, incurring the charge (and earning the SPG points) and then cancel hte other one to offset the new charge?

I wouldn only do this once as I don't want to raise any red flags with Amex, but if i can do this legitimately I could get a nice new bunch of SPG points.