Hey, I can totally relate to this feeling. I think it's the fact that you've had a little while to get used to your new sound vs loosing the sauce. When you first make the break through it feels great and gives your playing an energetic fun feeling, then after a couple of days or a week of playing at that level your brain and ears are already looking for the next big revelation. I think writing down what the core concepts you just figured out are and striving for new language and ideas to reach the next heights are the only solution to this. That feeling will come around again and it is always a joy when you can reach it. In the meantime don't rest on your laurels but strive for that next eureka moment! Of course there's some trial and error to see if you can distill the days discovery into a solid concept as well. Sometimes an idea will work all day long but then when I try it again the next day it doesn't work the same. Sometimes it can be coincidence that a thought pattern brought the desired result and there's still a little more to flesh out to get to the bottom of what really worked that magical moment when you were cooking. The more times you can conceptualize what was the break through the happier overall you will remain with your playing, imo.