The real secret to conquering creative burnout and keeping your edge is to prevent your imagination from stagnating in the first place. Try one or more of the following:
1) Keep a Journal: Write these pages every morning. Doesn't matter what. And carry it with you during the day, just in case.
2) Add"change" to your routine: Move your desk across the room. walk a different street. Read someone else's magazines (but ask first)
3) Study a new technique every week: Change brainstroming techniques the way some people ought to change their toothbrushes often.
4) Chill: Ever get an idea while driving? Taking a walk? In the shower? The subconscious does a lot of work while you are relaxing.
5) Paint, draw, play music: Skills that force you to think creatively - but to do things alien to your routine - can jumpstart a slumbering mind.
6) Practice problem solving: Musical people often learn languages faster. People who do crossword puzzles live longer and stay sharper. The mind, it turns out, is a muscle.
7) Read: Walt Disney called Reader's Digest a "gymnasium for training the mind". Even better might be to read some history and science books also.