She has LESS knowledge than she had on Sunday in one critical area - because now she doesn't know what day of the week it is. She may not have learned much - but she has definitely forgotten something -

That's true.

and forgetting things changes your estimates of their liklihood just as much as learning about them does.

I'm not as sure about this. It's not clear to me how it changes the likelihoods if I sketch Beauty's situation at time 1 and time 2 as

1. A coin will be flipped and I will be woken up on Monday, and perhaps Tuesday. It is Sunday.
2. I have been woken up, so a coin has been flipped. It is Monday or Tuesday but I do not know which.

as opposed to just

1. A coin will be flipped and I will be woken up on Monday, and perhaps Tuesday.
2. I have been woken up, so a coin has been flipped. It is Monday or Tuesday but I do not know which.

(Edit to clarify - the 2nd pair of statements is meant to represent roughly how I was thinking about the setup when writing my earlier comment. That is, it's evident that I didn't account for Beauty forgetting what day of the week it is in the way timtyler expected, but at the same time I don't believe that made any material difference.)