I like the suggestion James gave. A week or two off after a cycle should be regularly followed advice. Also, make sure that during PCT you lower your level of training intensity.
Maybe look into changing your routine up, add in different lifts, do a different split, pair up different body parts to work, find a partner to train with, etc. One thing that keeps me going are the many compliments I receive from people, and this board.
We all fall into a bit of a lull at one time or another. We just need to make a change, or rediscover what it is that motivates us.