I have a 7 year old lab. I put her through some of the same drills that I used when training her initially, such as blind retrieves, handling, and marked retrieves. Most of these drills are for retrieving so they may not apply to your GSP. One drill that may apply to you is to find hidden bumpers. I will plant a few scented bumpers in a big field and command her to "hunt 'em up". Then I follow her as she hunts for the bumpers just like we would hunt pheasants. A friend of mine, who has a smaller area in which to work, will stand in his front yard and launch a bumper over the house into the back yard and command his dog to go and find it.
These specific drills may not be of use to you but perhaps there are other drills that are used to train pointers that you can use.
