Patience is probably the best choice. That is by no means the easy choice though because it doesn't really address any frustration you have. I'd guess that a "pause" or "stepping away" is preferable to continuing to play but behind your back or being excluded intentionally.
I would agree with you regarding the cumulative effect of her getting in better shape and how that affects her overall confidence and self image. You'd think one day she'd look at herself in the mirror and say, "Lookin' good girl!" That should remind her of her playing days and possible desires to go again. Then again, it may not be anything other than just a healthy focus.
It makes me think. If she's confident about herself being attractive, then maybe her choice to slow things to a crawl is more about the lifestyle and whether she really wants it. There's a chance that she may see it as a predictable dead end. She may even not like the way she sees herself and upset with herself that she became comfortable with it. Or, I could be way the fuck off, just thinking of the possibilities.
One thing is absolutely certain, she knows what you like and she knows she's not doing that so much. She knows your kink and what gets you going. She has to know that she's not doing that. It has to be something that she thinks about. Has she initiated any conversation on the topic? If it was me I'd wait until she did and not bring it up. She may be anticipating that.
I guess a big question is if she calls it good and wants to put in the past, would you be cool with that? In a lot of ways you've had more fun and experience than most already. If by chance there are still things that you yourself want to experience, is there any way you could tell her without it coming across as a complaint or dissatisfaction?
I can see how "landing the plane" (ie ending the lifestyle) can be tricky. In an ideal world you are both ready to quit at the same time. Otherwise, there has to be some tension from one wanting to quit and the other not.