Mostly the books I have read more than 3 times were those I read in my childhood. The first book that came across my mind is Harry Potter and the Prisoner of Azkaban. It was one of my favorite book in the series. Since Thai edition of book four was delayed for years or two, I have read book three over and over again since it was my favorite out of three available books.
I would like to include another book but I saw that there is a challenge on Day 21. So I will talk about that book on that day instead.