How can I help mys students memorize lines?

The school where I teach is putting on “The king and I” this weekend, and our male lead still does not have all of his lines memorized. Memorization has never been a problem for me, so I have no further suggestions than “read them over and over again.” If you have had past difficulties with memorization and have overcome them in a relatively short amount of time, what did you try? I’m looking for almost anything short of tattooing them on your body.