How do you balance "production"
First, I have to explain what "production" and "creation" are in relation to this question. Raven's Whimzy explains that she "end(s) up doing so much shipping, bookkeeping and production" like making multiples of items that she finds herself with "very little time for actually creating new things." Production vs. Creation. Pretty simple.
With the holidays coming up we can all use a lesson in time management and prioritizing which, in my opinion, this is all about. I suggest setting aside a certain amount of time, no matter how much you have to do and how many orders you have to fulfill, to just create. Spend this time brainstorming, sketching, and making prototypes. The technical sides like researching material costs, pricing, market research, or planning a launch shouldn't be included in this time. While this is all part of bringing a new product into being, it isn't about creating. By prioritizing time for creation, you may have to extend the time period for order fulfillment and make your customers aware of that. This may especially be the case if items are made to order, but a simple statement along the lines of "please allow 1-2 weeks for item completion" can help everything.
Following the footsteps of linkmaster, jswrites, here are a couple of links to help. There's "Organizing for the Holidays (And Beyond)" and Lillyella's recap of her virtual lab session on Organization and Time Management. While everyone has different commitments everyone can find a chunk of time to commit to creation. Whether its an hour a week or an entire day doesn't matter. Use what time you can!