Lisa Levy's post on The Millions about rereading reminds me of a class I taught at Stanford called "Does Literature Matter?" One of the assignments was to reread a story, book, or poem that meant something to you in the past, and write about how you and the story had both changed. This assignment always seemed to produce the best papers. As Levy suggests, I think that's because rereading generated multiple layers of reflection: yourself then, yourself now, yourself now seeing yourself then. And somewhere in the middle, the "text itself," which is always changing as its readers change. To reread is to consciously experience the fluidity of yourself, and all the things that surround and bolster your "self."
That all sounds great and important. And yet I, myself, am not that much for rereading. I suspect I'm afraid of being sucked into the past, and/or former selves, many aspects of which I would rather not dwell on or in. When I do reread, I tend to do it for some purpose other than pure pleasure: for the Borrowed Fire experiment, or to study techniques of a writer I admire (which is really the point of BF anyway). Those are partly the hazards of being a semi-professional reader.
What do I reread purely for pleasure? Popular science books mostly. Maybe that's because my own emotional history isn't bound up in them. There aren't a lot of places in them to deposit one's hopes, fears, and dreams for later--possibly blindsiding--retrieval.