You take away some of the solder resit, like a tiny bit around the mouth of the pad.
Clean up the where the pad is going to go and the glue down a tiny piece of copper (you buy thin sheets of copper to do pad repair).
Then bridge some solder between the exposed part of the track and the new pad.
But how badly have you damaged the pad? If it's just lifted be very careful and attach a wire to the loose bit of pad after gluing the wire somewhere close to the pad so that it doesn't move and rip the broken pad off when you're finished. Even better, get some epoxy reattach the pad to the board.