Nickelodeon today said it plans to air 20 new episodes of “SpongeBob SquarePants” during 2005.The new episodes will be executive produced by “SpongeBob SquarePants” creator Stephen Hillenburg and feature the original voice cast, including Tom Kenny as SpongeBob. Mr. Hillenburg is also overseeing the upcoming “The SpongeBob SquarePants Movie” from Nickelodeon Movies and Paramount Pictures, which will be released Nov. 19.