It's not just changing the form of your creative endeavor, i.e. going from short story writing to manga writing that increases your ability with all writing, I've realized.
If you want more story ideas, bake cookies! Especially if baking is way out of your comfort zone. Even if you love to bake and "tweak" recipes all the time, then make up your own.
That way, you get all those synapses firing away and creating, creating, creating.
Secret: Stuck? Frustrated? Do something completely different!