If you did decide to breed her again and you wanted to have color as well as a registered foal, couldn't you breed her to a saddlebred stallion and register the foal as a National Show Horse? I had a gelding that was arab/saddlebred. He was registered half arab and he could have been registered NSH. We didn't breed him, I got him as a foal, but he was a really nice horse. He did pretty well in local hunter shows and now he is doing dressage with his new owner. I don't personally think you need to breed again, you could buy a foal and know exactly what you are getting for the same investment. I think your mare is very cute and you should just enjoy her.