Yes, there is a shuttle. The pickup/drop-off location at PBH is near the entrance. The bellhops should be able to point you to the correct location. At RPR, the pickup/drop-off location is at the business entrance instead of the main entrance. We used it once to get from PBH to RPR and we waited about 20 minutes for the shuttle to arrive.
My advice is to use the boat transportation. Its relaxing, plus the RPR pickup/drop-off boat location is very close to Tchoup Chop entrance.