Dragonball Reborn is an upcoming 2015 live-action science fiction film strongly based on the Japanese Dragon Ball Z manga. It will be directed by Stephen Chow and produced by James Wong. It will be released by 20th Century Fox.
Dragonball 2: Reborn is still awaiting to be fully confirmed, although the original cast from the previous film seem to be fully ready as they too are awaiting a confirmation.
Both Justin Chatwin (Goku) and James Marsters (Piccolo) have signed up for at least two more films. It's uncertain if the rest of the cast will return for a sequel, they might for a higher salary.