Fox is moving forward with a sequel to Rise of the Planet of the Apes and has hired a writer to polish up the story. According to THR, Scott Z. Burns (Contagion, The Bourne Ultimatum) is writing the new screenplay which will continue the story from the previous film:

"The project continues the story set forth in last year’s critical and commercial hit movie featuring simians that are given human intelligence and subsequently break out of their facility. At the same time, a virus breaks out that causes the collapse of human society.

The new project is taking the story to the next level, with the apes on the path to emerge as society’s new rulers."

Andy Serkis and director Rupert Wyatt have already signed on, and the first film's original writers Amanda Silver and Rick Jaffa wrote the first draft for the sequel. No official release date has been set, but Fox previously mentioned that they are looking at summer 2014.