Happens to me alot. I have trouble sometimes just finding the motivation to go into he shop. Not because I don't like it, but because I am not ready to start another "session". I am kind of obsessive when i start a new project. It gets to the point where I have to force myself to go leave the shop and get a couple of hours sleep before getting up to go to the "real" job.
One thing I do when in a slump is change up projects or try something new. Heck I have made candle sticks, salt pots, ht ovens, etc. My next deviation is going to be making pens for my mom and dad for their xmas gifts. Now that led me to ss damascus as the material, now I need to figure out how to do ss damascus.
I would suggest trying something new, not even related to knife making, but using the same skills that making knives gave you. While you are working "off topic" I would be willing to bet that your creativity will return.