Season 3 probably will not begin in 2013.
Season 3 of Sonny With A Chance will probably not resume in 2013, due to the fact Demi Lovato has left Disney Channel, possibly for good. Also, Tiffany Thornton had a baby in August of 2012, so, she's busy being a mom. Also, the main cast is probably doing other projects besides the show. For instance, Demi was a judge on the U.S. version of the "X Factor".