Should I sign up for a lower level lesson then if I do? Like, a step or two below where I was before?
From my experience, it's not the level of the lesson that matters. It's the experience of the instructor. After that, it's how much you are willing to mix in practice with runs just for fun. Lots of ways pay closer attention for a few turns even while mostly just skiing.
As an example, I have friends who have taken Intermediate lessons at Alta during midweek. One was an advanced skier during a midseason trip. She got to work with one of the most experienced L3 instructor at Alta Ski School. Signed up for a semi-private lesson with that instructor later that week. Another friend was a cautious intermediate during a spring break trip with her kids. She had three consecutive solo lessons with a L3 instructor with about 30 years experience, 20 at Solitude before he moved to Alta Ski School. He had her move from greens to easy blues that week. Her total skiing experience at the time was about 5 days at Massanutten over three seasons, with a lesson each of the holiday weekends I went with her and her kids. The kids were relatively young, so each of her ski days probably included at most 4 hours on snow, including long waits for the beginner lifts the first couple seasons.
At Mnut, there are times when L3 instructors (or equivalent years teaching) are in line-up for the adv. beginner/intermediate lessons. Needless to say, they teach the most experienced students. My daughter had a few very good lessons when she was a tween as an intermediate. I made her take a lesson at the beginning of every season after she was old enough for clinic and less interested in ski school. Did the same for my friend's kids when they became tweens. Had I known what I learned later, I would've taken some intermediate lessons at Mnut myself.
I've had quite a few lessons in recent years that included people who were at a lower ability level. Sometimes friends for semi-private lessons, sometimes group lessons. The way I think, I've found that I can learn a lot observing how an instructor teaches someone else. I'm a visual learner, especially for sports. It's very helpful to see what a slight change can make in someone else's skiing. For instance, standing up a little taller or getting their hands in a different position.
My thinking about group lessons might be rubbing off on my ski buddy Bill. He was an advanced/expert skier in high school in Colorado decades ago. The last two seasons he was in a Taos Ski Week at the highest level, with the same instructor both times (6 consecutive morning lessons). His group was skiing double-blacks (seriously steep terrain with bumps and trees) most of the week. Last week he chose to stay in a lower level Ski Week that worked on blue bumps and only did black bumps later in the week. He said he wanted to work on fundamentals. After a run one afternoon down some blue bumps, he said that all the little pieces he's learned over a few years had come together for a few turns. Can't work on the subtle points of advanced technique on challenging terrain.