I have always loved rereading. I did it a lot as a child, mainly because I didn't have as many books to read as I would have liked to, but also for pleasure.
Nowadays, I reread to revisit characters or fictional worlds I particularly like. The books I have reread the most during the past decade are the Harry Potter books, and I am currently rereading George R. R. Martin's Song of Ice and Fire series.
I also reread Connie Willis's stuff, mostly her time travel books.
Lately, I do a lot of rereading by listening to audiobooks, which is of course different but very enjoyable, at least to me.
Another set of books that I have reread earlier this year is The Sparrow and Children of God by Mary Doria Russell.