The pads are double sided, so if the bottom side of the pad is still fresh, you can simply flip it over and reuse. Otherwise you'll need a new wiper pad to install. We include a 5 pack of wipers with each Mini, and they're also available on Lulzbot.com.
Take the new pad and slip one end of it into the wiper mount as shown.
Bend the wiper pad to get the second side inserted into the wiper mount
Press the wiper pad into the wiper mount using your fingers, make sure that it's just about flush with the top surface.