This. I suspect the theater needs top-to-bottom electrical, plumbing, HVAC, and finishing work in the same way many of the park's original 1990 builds do (hence why Finnegan's is also going under the knife, as Mel's did before that).
I'm guessing this work can't be prudently put off any longer, as many building elements have likely reached the end of their expected service lives. Refreshing the show itself is more of a bonus to get another marketing bullet point and help justify the expense.