Say, have you ever heard of Art Fight? If you are ever interested in something to motivate to draw more then you should definitely try entering next year!
I find that participating in art fight is the most rewarding way of practicing art. And it really is motivating I did more art this year during art fight then i did any other month.
It's competitive in a fun way. Plus you might even get art of you own characters as well.
The event is hosted each year during the whole month of July.
Sorry if this comment seems off topic, but your challenge really reminded me of this.