When Disney updated Star Tours in Disneyland and Walt Disney World a couple of years ago, one of the big improvements was an all-digital system for the ride film.
The original version of Star Tours actually used a film strip that contained the ride film, and it ran continuously from the rear of the Starspeeder, to the front, and then back. Basically in a loop and the way the system worked, the film had to run its entire runtime each time the ride was started. The downside to this was also that the ride was always the same and changes couldn’t be made without making an whole new film.
With the digital upgrade, the whole thing works differently and the random nature of the ride now works like a slot machine. When the ride operator hits the button to start the ride, the slot machine begins and a random opening, intro planet, hologram, and finale planet are slotted in, which is why every time you ride it you get a different experience. The bonus to this is that new destinations can be slotted in at any time.
Disney has been rumored to have a few new destinations ready to go at any time (such as Alderaan), and now the Disney and More blog has heard that they plan to update the ride in 2015.
As 2015 is both the release of Episode VII and the 60th Anniversary of Disneyland, it makes sense for them to hold the update until then.