Practicing difficult passages of music is not particularly exciting for most of my students. They prefer to practice music they can already play :)
Jigsaw puzzles can help! I put the puzzle together while the student repeats the tricky passage. Each time she plays the passage, I put another piece to the puzzle until it is complete.
Use small puzzles with 4 to 12 pieces. I guarantee that a 500 piece puzzle will not be greeted with enthusiasm!
These are resources we use/create to encourage our students to practice, practice, practice!