'When I re-read The Rainbow I had thought I might discover, like a flower pressed between the pages, the dried remains of my younger self preserved within it.' (Geoff Dyer - Out of Sheer Rage: In the Shadow of D.H. Lawrence)
This quote encapsulates for me why sometimes re-reading an old favourite can sometimes be a little disappointing. Haven't we all had that experience of going back to book or film that we loved when we were younger or that really resonated with us, only to discover that it just isn't as good as we remember or worse still that it leaves us cold? How much we enjoy a book isn't just about the quality of writing, or the way the story engages us (the readers) - it is about the experiences that we as readers bring to the reading of each particular story - our state of mind, our life circumstances, our past experiences etc.
It makes sense that we respond to texts differently at different points in our lives - after all our life experience at sixteen-years-old is going to be vastly different to our life experience in our forties - and what seemed new and exciting to us as teenagers may seem like stale and hackneyed ideas to us as adults, or things that seemed plausible may seem less so. But I think also that Dyer has nit the nail on the head - when I re-read a book there is almost certainly an element of wanting to re-capture the original feelings it engendered in me - whether these are recognition, fear, excitement or whatever, and part of that desire might also be yearning to re-experience what it is like to be a younger version of myself. Of course this is next to impossible - unless you have amnesia you can't read a book you have already read and expect to have the same reactions to it as the first time you read it. We can only really experience something for the first time once, so on subsequent readings we will not only be bringing the life experiences that we have accumulated since the reading, but also our memories and thoughts (both conscious and subconscious) of the book to the reading experience.
Of course that doesn't mean that we shouldn't re-read books or that we won't enjoy re-visiting novels that we have already read. Often a re-reading of a book can be enjoyable in a different way to the first reading, it can remind us how we felt when we first read it, and, perhaps more importantly, it can lead us to a deeper understanding of the text.