This happened to my daughter at Level 8 regionals, several years ago. Her music stopped for a few seconds, came back on for a couple seconds and then stopped completely. She pretty much performed her routine without music and music coming on and off threw her rhythm out. The audience helped out by clapping to keep the rhythm going. Her HC asked for a redo and was granted one. Well, like your story, my daughter did so much better the second time and ended up winning floor.
As stated by several posters above, the coach has to ask for a redo. Before my daughter was granted one, they made sure the music mishap was due to the meet’s mishandling and not a defect in the music provided. Also, keep in mind if your daughter’s coach does not think your daughter can do better, why would she risk it? Your daughter could make a mistake in her second routine that could drive her score lower. My daughter’s coach was told my daughter got a good score but she took the gamble and it paid off. But it certainly had risks.
One other time, at our home gym, at my daughter’s first Level 7 meet, she was robbed of being 2nd all around because of a computer calculation error. The coaches came to me the Monday after the meet to tell me. I wished my daughter got that acknowledgement but when I told her, it didn’t seem to matter. She learned her first floor routine 4 days before the meet. So she was just happy to pull a 4th AA placement.
The meet is over. By the next meet, whatever win or loss your daughter had would be forgotten. Time to think of the next meet.