To Re-read or Not Re-Read

Yesterday one of my librarian pals had a question in her facebook status. The question was "When it comes to the Harry Potter books, how many times is too many times in regard to re-reading?" My response? You can never re-read them too many times. I am a huge fan of re-reading novels. I don't know how many times I have read the Harry Potter series, and each time I love them more and more. There are numerous other books that I have read over and over again, including Nick and Norah's Infinite Playlist, all of John Green's books, Twilight, and many more. I also do this crazy thing where if a book is part of a series I have to re-read all of the previous books each time a new book comes out. Part of this is due to the fact that I read so many books and part of it is that I don't want to have memories gaps when I am reading the newest novel. Also, a huge part of it is that I just love books. It is rare for me to hate anything that I read, and if I love a book I want to experience it over and over again. So, how do you all feel about re-reading books? And if you don't re-read books what do you do with books you purchase after you have read them once?