Room & Board refunds, 529s and taxes

I just got a refund a couple of weeks ago, and it went automatically into the Checking Account which is what the school preferred for faster disbursement and any potential misplace of the check in the mail.

My question is this: I am planning to take a courses in summer for which we have to pay by mid May. Does it make sense to use the refund against the summer course or go thru the hassle of sending it to 529? I was actually advised by the 529 plan to mail a physical check with a cover letter saying it is re-contribution. The physical check and letter is for my own records, as they will consider it as a new contribution. I did not ask about using it for the Summer (as I did not decide at that time for summer!)

I see from above (Pennlive & TS014), that I could use it as long as it is in the same year 2020.

Thoughts/Advise please?