Well, you could force enumeration:
By sending something to your device to make it disconnect.
By sending something to the controlling hub to make it disabled/enabled.
But it's better to leave everything connected.
Doesn't Windows scale whatever the touch screen is to what the screen is (at least for a single screen)?
Can't you just report the range as [0, 0] to [65535, 65535]?
Then you can scale/rotate the touches on your side.