For the Star Wars dessert party, with a capacity of 140, assuming all adults at $70/each, that comes to ballpark $10K (very generously). I've seen Wishes quoted as over $40K a night, so if the Star Works show is just a quarter of that, the dessert party is just covering the cost of the show (since no one else is paying specifically for it), without even considering th cost of the party.
But let's say we don't apply the income against the show costs, since they'll have the show anyway. $10K/night comes to $3,650,000. A new ride can run $100,000,000. So that's over 25 years before the Star Wars dessert party could pay the cost of a new ride.