This question What is the relationship between how time is viewed in thermodynamics and how time is viewed in general relativity? is close to what I was wondering, but it didn't get into repetition specifically.
I'm not a physicist, my Scientific American level of understanding is that the universe is constantly changing, I think that is specifically the changing state of entropy, and that constant change is what creates the arrow of time.
Nothing is ever truly unchanging and so the constant change is how we perceive time.
But doesn't repetition fit in somehow?
If some state of the universe repeated, wouldn't that be a reserving of the arrow of time?
I suppose the answer might simply be no, and if I am confused by the repetition, that's just a problem with my perception.
But, anyway, do these theories of arrow of time and entropy say anything about repetition?