Whoops! I guess it's time to retire the 916 and get a modern bike.
Also, the comment about water in the clutch slave cylinder is a good one. The engine temperature at the slave cylinder location can easily reach 212 degrees F (the boiling point of water), and nearby small pockets of water, as they boil, introduce water vapor in the line that causes behavior just like air in the line does.
The amount of water that hydraulic fluid can hold in solution is dependant on the temperature of the fluid. So, The Ducati clutch hydraulic circuit is like a little water generator. When the fluid heats-up from engine heat, it can hold more than five times more water than it could hold at room temperature. Moisture usually enters through leaks in the reservoir cover and gets absorbed into the fluid.
Then the fluid cools down when you shutdown so the additional fluid that could be held at the higher temperature, condenses out into water droplets that sink to the low point of the system - to the slave cylinder. This happens over-and-over until enough water has accumulated at the hottest point in the system. At 212 degrees F it boils and your clutch actuation goes south.
So, flush your system to get rid of the water completely.