Do I have to replace the MF100 microfiber cloth after every window and can it be left on the VG100 after use?

You do not have to replace the cloth after every window.

However, every time you refill the fresh water tank, we recommend emptying the waste water tank and replacing the MF100 microfiber cloth.

Once the windows have been washed, the cloth should be washed to prevent an unpleasant odour from developing.