Yes, you will need to remove and re-add the items for now. The cart is pretty rudimentary - it's meant as a convenience for a single shopping session, not really meant as a persistent thing, so it's just a list of items and their prices at the time they were added to the cart. It was supposed to expire after a short amount of time (like 1 day or so) so that this wouldn't be an issue; we could also try to clear cart data any time we change prices or change items in stock. I'll have to think about how best to handle this.