Hi Jason, I don't have a lot of experience with retrieving trials but I do have a young dog who was doing similar to your dog and was reluctant to deliver to hand and would rather turn it into a game. If I put a long line on him as Dianne suggested, he shutdown. One thing I have had success with is that I changed the picture of him coming back to me - I took a fold up chair out with me, heeled him forward a way from it and would leave him there whilst I threw the dummy, walk back and send him. Once he was committed to returning to me and was about 3/4 of the way back, I turned and ran for that chair and sat down to face him, legs apart, to encourage him to come in as close to possible to me. My dog has a high chase/prey drive thus the movement of me running backwards encouraged him to chase me and I am only just beating him to the chair, so then he was right there as I turned around. In the early stages of this game, I didn't demand a hold, or sit in front etc, I just wanted the return. As we progressed, which was quickly, I was then getting a hold and delivery to hand and eventually a sit in front (cued), which is what I want. I also used some treats (and tons of praise!) during this process although the game is more motivating for this dog than food. This work was done on an oval, keeping it simple. Progression is to turn the chair around and you then lean against the back of the chair, with knees bent and still apart (so you are not yet standing upright), to encourage that return in front. Eventually you move to fully standing up again. After despairing about my young dog and hand delivery, he did a beautiful 70 metre mark, retrieve and sit in front hand delivery for me this morning I also kept reps of the above short and training sessions short, but all of the above was done over only a few weeks.
The above method is taken from several positive obedience trainers both from Australia and the UK and is based on how they introduce retrieving work for obedience as well as fronts for recalls and other obedience work.