I wouldn't actually mind them de-aging Aunt May a bit in the comics. It doesn't need to be anything magical or any cosmic reset. Just say that the doctor discovered a previously undetected condition and gave her medicine for it and now she's feeling a lot better. Then slowly start drawing her looking a little bit younger every few issues. You could even have her dye her hair. I know lots of older ladies that dye.
Although I do feel you'd have to be careful about this to not make her feel too much like a new character or something.