Thanks for the compliment. I step on the mat with the student mind even though I primarily teach. And I have never yet stepped off the mat without learning something new-every class-it may be a subtlety or something real simple but my mind expects to learn something new and I do.
To avoid the teaching the same old thing every day, week, etc. I try to avoid that by not having any idea what I am going to teach when I step on the mat. I basically don't have a pre mindset for the days lession. I may do something based on a comment I hear before class or an observation of another instructors class before mine. I also periodically ask students what they want to work on. The only time I focus on teaching specific material repetitively is when we approach test time. So far, I've been lucky and have not been at a loss as to what to teach.
The ideas of mixing things up is good. I sometimes take a beginners group and teach them oyo waza. It actually helps their basics when they go back to them.