Do you have access to sand bells? Although it’s not “new,” sometimes it’s a nice variety to mix up regular kettlebell exercises with sandbells. The grip and balance are a bit different.
Sometimes, I’ll start with a heavy kettlebell exercise (where “heavy” is defined by and relative to the client) to pre-fatigue, then move to the same exercise with a sand bell as a finisher.
Another thing I like to do is alternate between kettlebell swings where the momentum is mostly upwards and sand bell slam + squats where the momentum is mostly downwards.
Are you doing circuits with various pieces of equipment, or just kettlebells, and what are your standard moves?
One idea to mix things up is to have a focus, or theme, for the workout. For example, you could focus on unilateral, or one sided movements, and incorporate kettlebell exercises geared toward that (example is one legged deadlift or one arm chest press with kettlebell). Another theme could be leg and cardio drills with kettlebells. You get the idea—sometimes a focus or theme makes the circuit new and interesting for the client even though some of the moves will be the same.
You could also take some of your same moves and make them harder by varying your time (both timing in seconds as well as varying the rate of speed for some exercises). Or increase the weight of the kettlebell and do fewer reps.
Hope some of these simple suggestions add a little variety for you.
YouTube has plenty of exercises posted there. I would also suggest the Dragon door website www.dragondoor.com. I hope this helps.
My favorite KB moves are:
Turkish Get Up (stability exercise): https://www.youtube.com/watch?v=8Zl83Gxx2ow
Single Arm KB Snatch (power): https://www.youtube.com/watch?v=6MGUllzX_0g
Single Leg RDL with KB (strength and stability): https://www.youtube.com/watch?v=g9p6-f_2x8w
KB Hip Thrust (glute activation): https://www.youtube.com/watch?v=RilW7cEDGE0
Hope this helps!