On no! That is a beautiful skirt...found this on google...
"I rubbed a little dish soap right onto one of our most recent stains and let it sit for a little while before washing. I sent the shirt through the wash and didn't see a stain, so I went ahead and dried it too. Like magic, the stain was gone.
I even tried this trick on old stains — ones that had been washed and dried repeatedly — and the clothes came out as good as new. I could hardly believe it!
I think it must be something about the grease-busting properties of dish soap that makes this work. Whatever it is, I'm glad to know about it."
I haven't tried this myself but it could be worth a try? I wonder if you could spot clean the skirt using this method?