I'm not sure what the exact process on PVC is, but on rubber I used toluene to soften the glue around the leak. Then I peeled back the rubber to get enough material free that I could keep the two pieces separated while the glue dried. Then I just re-glued everything I had lifted up, making sure to follow the manufacturer's directions for letting the glue set-up.
If you want a quick and dirty job, you can patch over the seam, just make sure you have maybe 2 inches of patch in each direction on the seam. Glue the patch on and use a roller or some other tool that will allow you to put direct pressure on the low side of the seam. Keep moving the tool over the low side to ensure a good bond with no air bubbles.
Again, I've not glued PVC before, but I believe the principles are the same. Well prepared surfaces, quality glue, attention to detail.