Yep, remove clean the area, to remove all the old glue,( I used MEK on my PVC dingy) rough up the surface, then depending on material PVC or hypalon will will determine which type clue to use. Typically the glue for these you put on both surfaces, let to set for 10-20 minutes, put on a second coat wait 5-10 minutes then apply the patch to the damaged area, with pressure.
Does it sound like I just finished this process ? Yea me too, good luck.