One of the things that I love about Pilates is how versatile the exercises can be. It is amazing how you can take an exercise from one apparatus and put it on another to give it a totally different feeling and meaning.
Have you ever taken the rowing series from the reformer and taught it with light weights in mat class? Try taking the frogs and leg circles off the reformer and put that in an advanced mat class without any footstaps. Talk about a wake up for your core!
Keep things fresh by showing clients different ways to do a familiar exercise. It's amazing how a new tweak on an exercise can become more engaging.