I'm more of a guitarist rather than a music producer, but I think this is pretty applicable. I think writers block may be even more common for an instrumentalist. It's just you and the instrument paired together, so it's natural to get into repetitive habits. Here are the two things I believe every musician must do.
* Make yourself improve. This can be practicing difficult new techniques, or learning about music/gear/programs/sound, or work on being able to reproduce something you hear, or expanding your music listening catalogue, whatever. This is the technical side.
*Allow yourself to create. This is the part where if you've done your homework and laid yourself a good foundation from the first step, you'll be able to shine. One thing you have to do is separate this from the first 'work' step. I'm hardly ever able to force myself to make new material I like, and even more so material that I'll like after a couple days. Where I am able to make decent material is when I turn on the blacklight and just jam or I'm just brainstorming at a band practice. The same goes for writing on the computer. I mean throw out some randomness to get the ball rolling, then visualize the music you want in your mind, and then make it happen.