1) They reuse most of their props every year. To a degree, the houses are designed around the props they have available. Because the Shrek house would be a last minute add, it wouldn't have been included in the initial "prop dispersal." So, basically, they wouldn't have a "complete" house ready to just reuse.
2) It's going into Shrek. So, whatever is getting put in there is a fresh build. They could reuse a layout, which isn't uncommon, but any decor work will have to be new. Unless we're getting one of the FEW houses that have been in Shrek (and the IPs are incredibly unlikely because of rights or timeliness) this will be a new experience.
3) I know two rooms for the house. I won't share them, but they are generic to a pointless degree. That said, those rooms would fit, literally, hundreds of IPs (including Purge, TWD, IT, Halloween, The Blob, A Quiet Place, The Exorcist, Nosferatu, Brooklyn Nine-Nine, and Frasier). There would be an infinite number of original possibilities with that.
But I'm certain it's not Alice again.
So, even if it's an IP we've seen before, it WON'T be an IP we've seen HERE before. It'll be a brand new house.