Have a couple of years driving a commercial CNC 40 hrs per week. THe compression bit cuts at the tip while plunging or ramping down, and along the sides the rest of the time. If you are lucky, you might manage to get a couple of resharpens from the bit, but I would not expect more.
To resharpen, they will dress the tip, which should not require any compensation, and then dress the lands of the helix to sharpen them. This will reduce the diameter of the bit marginally, and you can reset the bit diameter in your software to compensate, but you need to be able to measure the diameter very accurately for this to be effective.
The number of times that a bit can be resharpened is limited by the initial height of the helical lands above the body of the bit, after a couple of reworks, there tends to be insufficient clearance between the body and the work, and the bit heats up while cutting and tends to burn the material.