[colpet]

Due to forgetfullness, replaying a game is often like enjoying it the first time. After 2 or 3 years, details of a game slip away, and by revisiting it, I can still experience parts as if for the first time.
As for rereading books, I find it is somewhat the same. Some books that I've read over and over (Silmarillion, LotR, etc.) actually improve with age. These are often detailed reads to begin with, and I always pick up nuances or subplots that I didn't appreciate the first time. Many times the first read is rushed, since you are anxious to find out what happens. It's not until the next time that you can slow down and savor every paragraph.
I think there is value in replaying/rereading, if only because you are a different person than you were when you first enjoyed the game/book. Time and life experiences often bring a different outlook on things. The books I read as a teenager can have a whole new dimension when read as an adult.