I recently watched some reruns of an old sitcom I loved as a kid. Then, I could watch one after another and be utterly entertained by the wacky plots, but now I found it tedious, boring, and juvenile. (No it was not intended for children.) Growing up, thirty years of life experience and exposure to other more dramatic shows has made me a more savvy and demanding viewer.
Seems logical to assume that readers get similarly savvy and demanding.
As an author, IMHO, you should be challenging yourself with each new story. Your abilities should be growing and you should want to show them off. Readers may dig it; readers may reject it. The Almighty Sales will speak with a voice like thunder and motivate your publisher. You may have to flaunt these shiny new skills within the construct of publisher expectations or give up your notion of receiving funds from their coffers and having their logo on your book spine...but if its a great story, why would they restrict you?
All the 'great' stories I can think of, in books, on the silver and small screens, have one thing in common: diversity.
RECIPE: Take one plot with heart, add: action, characters I can get attached to (invariably taking big risks). Steep these in some element of mystery or the unknown that the character must uncover, and sprinkle with romance. Add heat and brew into a cohesive tale.
So challenge yourself! You do something you haven't done before. Maybe you swan dive into another genre like the ambitious Monday Man-whore Moore. (FYI, that is not a character besmirching statement--he is a fine chivalrous gentleman, but he blogs Mondays, is a man, and we are word-whores.) Maybe you test the waters by invoking some suspense and mild horror into your usual Urban Fantasy. Maybe you slip a little romance and mystery into your Sci-fi. (Mind the rules KAK provided yesterday.)
Try mingling those genre flavors into a medley that works for both your particular tastes and the demands of your story. The concoction may not be for you, and then again, that mishmash may be the best thing ever.