Here, try this once a week, for about 3 weeks:

Warmup until your legs feel a bit open, no minimal time. Then, while seated with hands on the drops or aero bars, shift into super easy gear like 39x19/21. From a slow speed, accelerate to a maximum pedaling cadence for 30 seconds. Recover for a full minute.

Repeat for a total of 6 efforts. Ride steady for 15 minutes, then repeat.

See what that does for your top end cadence, outside of making you want to puke.