ok, thank you for being incredibly specific, I will be updating this fight within the next two weeks (I hope), (changing the placeholder CH5 shadowcrystal attack, modifying dialogue a bit, making a longer ending scene, adding an option to nerf stars, etc.) and should be able to fix this
Viewing post in DELTARUNE - Alternate Ending - Chapter 7A Kris VS Susie comments
And now that I know that, I can locate the issue easie...r...
I see the problem
I forgot to put the 'check for death' thing in a loop upon subsequent attempts.
And the way 'check for death' works is:
when Susie's HP is less than 1:
Check if 'HOPE' is active
If yes, set HP to 1
If no, die
but on subsequent attempts, this was not in a loop, so after it triggered once, (and hope was active, so it didn't kill you), it just... stopped
So it turns out I'm just stupid I think