Some children will reread and some won't. My DD9 did not read HP till 8 and has since reread the whole series at least 8 times. This is great in the sense that she has surely wrung more meaning out of it than on first read--but still, there is much she cannot "get" yet by virtue of being 9. I hope she'll reread again when she is closer to the teen years.

I know some kids who read the series once, or had it read to them, or worse, just saw the movies, and considered it done and over.