I’m far from being an MTB god, but I’ve found stopping at a particular feature and “sessioning” has been useful after having a similar feeling of plateauing a bit.
Pick one thing and try and figure out how you could do it differently (not always better, just differently).
Mine was fast berms, I thought I’d hit the limit of how fast I could take them as the front wheel was washing out, then one day I tried exiting much much tighter, a few corners later I found that pumping even harder with my legs ‘lifted’ the front wheel (remember your lent over, so actually moving sideways), which both added speed and meant I was in a much better position for the next corner.
That added speed also meant I carried a lot more speed into a section of jumps/drops, which meant I improved on those too. There used to be one drop/jump/stepdown I wondered how on earth you were supposed to make the landing (the last ‘big’ one on Red25 at Swinley), now I’m clearing it easily.
All from figuring out how to ride berms tighter.