Many writers draw up outlines prior to starting a story, and many others groan at the thought. But whether you start writing when you have a fully formed plot or only a few lines of dialogue, an outline can be a useful tool in revision.
Outline, or write on index cards, your plot points. Make yourself take a step back and look at the overall story. Are there points when it drags? Do you have pages of description, or whole scene of spectacle or special effects, where the story doesn't move forward at all? Consider cutting or condensing the scene/pages or, if your story supports it, adding in at least one plot point to the scene.
This exercise can also be useful for character development. Map out the plot points relevant to one character - perhaps to your part in the play. Does your character grow and change over the course of the story? The more characters with a strong character arch, the more interesting the story.