In all of the old fairy tales, the characters shoes would represent aspects of their ******s (e.g. virginity, masterbation, rape or just their ******)
So in red shoes when she was thinking about her shoes in church, she was thinking about sex, and then after she couldn't stop "dancing" in her "shoes".
then when she gets her feet cut off, she is really cutting herself away from that part of her life and becoming a nun.
I can't quick remember where I read that, but it was a very interesting book.