Like others said, it is a good thing you are looking for ways to improve as an instructor.
I also have been feeling different teaching and not feeling the same fun like before. Check to see if you are doing too much, maybe you are tired and need a break?
What I did for one of my classes as i was feeling the motivation and atmosphere was not there anymore, I brought a piece of paper and asked them to make song requests for the new profile and surprisingly, many came after class to make requests. Not only this made my job easier to select music for new profile but I loved almost all of their selection and they Loved the new profile with their own music in it. It made the class a little more alive.
I also want to say that sometimes, what you feel is not always true. For example, I finished a class this Monday and I felt down as I thought class was not great and that it did not go well. But surprisingly, many people were thanking me and said it was a great class. I was happy to hear that people did enjoy it at end.