I, personally, prefer that they focus their limited resources on new mazes.
Houses need to be replaced fairly regularly, in part, because the industry evolves and innovates. Nostalgia aside, a great maze from 5-10 years ago won't have the current "technology" (for lack of a better word). Part of what made mazes like Bayou and No Vacancy so popular when they first opened, was that they were novel and cutting edge.
It is bad enough that both Virginia parks have been keeping old mazes open well past their prime and that they have also been adding unimaginative houses that lack up-to-date concepts. Going back to an old house, in my opinion, would just compound the problem of both haunt events feeling stale and uninspired.