I sometimes reread books for different reasons. I reread The Plague because the first time I was struggling to keep the characters apart and I wanted to discover some details I didnt catch before. I reread Learning Not to Drown by Anna Shinoda bc I couldnt remember the whole plot and I was in a reading slump and knew itd get me excited for reading again. I reread that popular book by Epictet (too lazy to look up the english title rn, sorry!) to memorize the content better. And I reread a book cause I wasnt feeling well and it's kinda a comfort book.
I really like rereading since I often forget parts of the plot or content and you often discover something new. Also its interesting to see how your perspective on a book changes over time. I dont do it often tho cause I have wayyy too many books i dont know yet on my book list.