You guys have all made good suggestions. However, there are plenty of things one can do to IMPROVE his/her game. I'm more interested in how to get out of a slump.
A slump is like a valley - there are mountains and hills surrounding it that make it a valley. You have the skills, the stance, the understanding, and the confidence to run racks. You have done it many times, but you're just going through a rough patch, one that doesn't have a clear answer as to why it's a rough patch.
In reality, there are hundreds of potential reasons. Stress from work, stress from home, loss of a job, bad mood, poor eating habits, the economy, the weather, etc etc. I think it's important to understand the difference between being in a slump and not advancing in skill level. You NORMALLY shoot a .780, but these past few months you're shooting a .410.
CHANGE SOMETHING. This can literally be anything - the point is that you shake things up, you force yourself to look at the table differently, you approach each shot differently. This has nothing at all to do with your skill, it has to do with being in a rut. You know how to drive your car, but right now you're stuck in mud.