This is a route that is currently flown at most 4 times weekly. As such, to expect an earlier flight to be added on the date that already has a late flight scheduled is almost certainly not going to happen.
Have you considered flying from nearby Florence? In the current schedule there are 11 weekly flights, made up of a morning daily flight, and a 4-times weekly flight at 19:45.
For next June, it appears there are up to 3 daily direct flights.