The problem is that when working with difficult stuff I reach the 80% level, and then something else catches my interest.
I know how you feel. Over the last 10 years, I have played hundreds of pieces but the ones that I could perform to any reasonable standard, I could count on the fingers of one hand.
Among many others I also found out that “Suite Bergamasque” of Debussy – at least parts of it – sounds very nice on the new piano. I played this suite (up to 80% level) some years ago and remember just enough of it to get an impression of how it may sound. I just wonder if I should make a new try and see if I can bring it to a new level. I think that I may benefit from the capabilities of the new instrument, and I have also improved my “technique of practicing”. So maybe.....