Our bunny does this as well, especially in the evening once we go to bed and in the morning once he hears us stirring. It's a way they try to get your attention. Playtime outside their cage is what he/she want.
If that isn't possible, I usually put a piece of a brown cardboard box in his cage...
This happened to my bun, too. My vet said that they go through phases with their pellets and treats. He compared it to humans...even if pizza was your favorite food, could you actually eat it everyday for your entire life? Probably not. As long as your rabbit is drinking, eating veggies/greens...
Also try syringing him some pineapple juice. It will help break up the blockage if there is any and also is hydrating and will give him a little energy.
Is he eating hay or any veggies? My rabbit wen through a phase where he stopped eating his pellets but the vet said that was okay. Also maybe try syringing him some pineapple juice...it's sweet and helps digestion.
I would be very interested, as well! My boyfriend and I do it ourselves but it's always such an ordeal (one holding and the other cutting). Our rabbit Q hates it and squirms so much that it takes a good half hour.
I'm always up for suggestions and tricks!