According to cabletvtalk.com, Season 11 of Pokemon starts on April 12th. It is currently unknown if the series will still be called 'Diamond and Pearl' or if it will be getting a new name.

"Pokemon Diamond & Pearl Season 11 Launch
The Pokemon Diamond & Pearl series continues with an all new season and all new episodes!

New Episodes Premiere Saturday, April 12th at 9:00am e/p, 19th, and 26th at 9:30am e/p"

Source: cabletvtalk.com