I don't remember a lot of details, but there's a fic where Clark is forced to relive the same day over and over and over and No, it's not the S4 Christmas episode. It's definitely set before Lois knows the secret, and I vaguely recall a bit where Clark nearly seduces her as Superman because he knows the world will just reset again.

Any loop recs are also welcome, of course.

I think you're looking for If At First You Don't Succeed... By ML Thompson.

If not, I highly recommend it as a great read.

Yes! That is definitely it!!

Thanks, Cuidadora! =D