Hi, Melinda! Depending on the mode that you're instructing, here are a couple of suggestions:
If you teach a cardio/toning format, consider switching to a toning/cardio format for a class-format change.
Again, without knowing what mode or modes you're instructing, if you're getting stale in the choreography department here's a trick that I've found useful (if a bit time-consuming) in the past to reshuffle things - LITERALLY:
Take all of your moves and steps, taking care to make them single moves (i.e. grapevine, chassee, step-turn, etc.), and write each and every one of them on a 3X5 file card. And separate arm movements from leg movements. Now, take the whole stack of file cards and shuffle them as if it were a deck of playing cards, and then take the newly shuffled stack by two-card or four-card, creating new combinations.
That might be the most helpful way especially with a senior class, where familiarity with specific movements is crucial for safety as well as effectiveness. Same moves, different combos. Never fails.
Also check out the Turnstep.com moves and patterns boards for ideas!
Hope this helps -
A-jock