Hey Dug...thanks for that note. We've bean weathered out several times and the excursions never showed on our account, and I wasn't really worried. Since I don't check my account every day I may have missed some temporary entries, but we never paid for anything we didn't receive so we never needed a "refund."
But to put the OP at ease, not to worry, Disney won't expect you to pay for canceled excursions. It doesn't happen very often that they are canceled, but if they are Disney as usual does the right thing. You will never need a refund since you never pay for it, they may have posted it but they don't charge you.