Artist vs. businesswoman

The other night I went out to make beads. I sat there for a long time in a creative block. Here is what I was struggling with: as my skills get better, as do my beads, I feel like making things I have already done (and have sold) is cheating. I realize this sounds ridiculous and, well, not sound businesslike. But it is the truth. I feel like I should always be creating, experimenting, trying something new, challenging myself.... and the more I do that, and the easier past beads become, the more I feel like "Ahh.. that design is too easy, I can't sell that." But the reality, I realize, is that its easy for me... not the buyer. They love the beads that I find, now, easy to create. So, I end up sitting at my bench for 15 minutes making nothing. Does this make sense to any other artist-types out there?? Maybe the key is to set aside "Production time" and "Experimental time." Any ideas?