The longer you stay at your new vertical jump level to more you will keep that level during rest etc…example, my vert is always around 32 inches when i do nothing, however this baseline used to be 24 inches the same as you but overtime it increased. Then it gets up to around 36-38 after specific training. This is totally normal.
When i played basketball full time i would spend all summer working on my vert. Plyos, squats, dead lifts etc etc…but once basketball practices started i never did squats or deadlifts or anything for my legs other than play basketball and my vert maintained all season. I’m not saying do what i did, as i know now that was a mistake but i’m just saying…if you keep some kinda jump stimulus in their, your vert should maintain.