I've read almost all my Star Trek books atleast twice. I have so many, that rereading them all a third time will take awhile.
There are several that I could reread a lot and enjoy them (Q-Continuum trilogy by Greg Cox, ST - TNG Reunion, Crossover).
As for non Star Trek books, I've read all the Harry potter books at least 3 times, and some 5-6 times. I've read the Lord of the Rings Trilogy about 4-5 times. I've read the three first Dune books about 5 times as well.
There are several that I could reread a lot and enjoy them (Q-Continuum trilogy by Greg Cox, ST - TNG Reunion, Crossover).
As for non Star Trek books, I've read all the Harry potter books at least 3 times, and some 5-6 times. I've read the Lord of the Rings Trilogy about 4-5 times. I've read the three first Dune books about 5 times as well.