Listening to music, playing Aetherlight, and sitting down to brainstorm are a few things that renew my inspiration when I am faced with writer's block. While brainstorming, I fill out a piece of paper with random ideas, lines of dialogue, and plot twists that I have yet to write.
In addition, it always helps to have an outline of how the story is to go. Then you only have to figure out how to get from point A to point B and finally to point Z. Sometimes you have inspiration in abundance, other times the words get stuck halfway between your brain and your fingers. When that happens, the trick is writing a little at a time to reach the next waypoint on the journey. Even though it's just a small step, it means your writing isn't at a standstill.
When all else fails, I bounce ideas off another person (usually my sister or a writing friend) and they can help me to get the creative juices flowing again.