It does include updating the room but here is the schedule for taking down the golden decorations and painting Cinderella Castle from an article on Mouseplanet.com. Your timing should still be ok to see the castle in all its golden glory -- no construction until September --
Article:
Castle to lose its golden enhancements
The new show for the castle forecourt stage will have a changed backdrop, as well. After almost a year and a half of golden characters, trimmings, and a huge faux magic mirror, Cinderella Castle will doff the decor and receive a fresh paint job.
It appears that a crane will arrive on site on September 10, and removal of the Happiest Celebration overlay will take place over the next few days. Once that's complete, the castle will be repainted, which is expected to take until December 5. The crane (which will be parked in the courtyard behind the castle) will reportedly be lowered during theme park hours, and only be active at night. The construction wall that will surround the crane will require the walkway from Sir Mickey's to the Fairy Tale Gardens to be closed, though the Gardens will remain open.