I've searched around some, and it seems that both re-read and reread are acceptable now. I have been eliminating the hyphen just because it seems easier. But I find I don't like the look of reread, so I guess I'm going to go with the hyphen from now on.
However you spell it, I am having the best reading time reading books over again. I mostly don't remember the whole story, but I have flashes of recognition sometimes. I kind of got started on this scheme because I didn't want to keep spending money on Kindle books. I am happy to buy a book that I can see; a book I can put on a shelf and look through anytime I want. I just can't do that with a Kindle. I am in high praise of the device because it is how I get to sleep and go back to sleep at night. Years and years ago, I read by lamplight. Then I had audiobooks on tape. Then I tried one of those itty-bitty lights. They were all distracting in terms of sleep, except for the books on tape. I gave those up when they went to CDs or phone. That was too much work for me in my sleepy state. And then the Kindle came along. It was perfection. But I've decided to read what I haven't read yet or re-read the books I have. And what a delightful experience it is. Just now I'm zooming through the Mrs. Pollifax books by Dorothy Gilman.
I wondered if there were quotes about this subject, and I found some great ones.
Robertson Davies: "A truly great book should be read in youth, again in maturity and once more in old age, as a fine building should be seen by morning light, at noon and by moonlight."
(To quote a word from one of my favorite books - The Diary of a Provincial Lady)
Query: Am I in maturity or old age?
Anne Fadiman: "The reader who plucks a book from her shelf only once is as deprived as the listener who, after attending a single performance of a Beethoven symphony never hears it again."
Italo Calvino: "A classic is a book which with each rereading offers as much of a sense of discovery as the first reading."
Garry Fitchett: "Rereading the works of a favorite author and, once again, learning something new shows me they are not done with me yet."
Lauren Groff: "The greatest texts, I think, first dazzle, then with careful rereading they instruct. I have learned from Virginia Woolf more than I even know how to articulate."
Susan Sontag: "Most of my reading is rereading."
and last, but definitely not least -
C.S. Lewis: "An unliterary man may be defined as one who reads books only once ... We do not enjoy a story fully on the first reading. Not till the curiosity, the sheer narrative lust, has been given its sop and laid asleep are we at leisure to savour the real beauties. Till then, it is like wasting great wine on a ravenous natural thirst which merely wants cold wetness."