For me, I would definitely change the color scheme. Bronze, teal, and maroon evoke a space wasteland as opposed to the future. I would repaint the entrance back to silver and add fiber optic lights (similar to the ones on the ground at Epcot) and repaint the rest of the land white, light blue, and blue with chrome highlights...everything chrome (make sure to put on those sunglasses on those bright sunny days).
In terms of attractions, I would like to see some type of space-themed ride that explores the universe (edutainment if you will).
Space Mountain would need another face lift...the escalators would have to come back, and this time, the track would be redesigned to incorporate inversions.
Like many others, the Astro Orbiter would be relocated to the top of the former People Mover/Rocket Rod loading station.
The Star Trader would not sell souvenir merchandise, but I'm not sure what they should sell instead...hmmmm, I'll have to think this one through...