Disengage.
Then come back. I'll bet you'll find you're more excited.
I've gone through this type of phase in the past. It's usually stress or lack of sleep, when it happens to me. In times when I'm happy and well-rested, I always have a background idea I dearly want to pursue.
Maybe you need to engage in creative procrastination. Find something boring you need to do for a while, then sneak time to have and work on your ideas!
Then, too, if I don't have a flagship project (so to speak, by which I mean a specific project I want to achieve) then I usually work on support structures that it would have been nice to have the last time around. Kind of a sharpening of my tools for the next job, I guess.