Disney's Doug - In February 1996, Disney bought Jumbo Pictures, and ordered new episodes of Doug to be produced (re-named Brand Spanking New! Doug and then later Disney's Doug). The new episodes brought a new baby sister for Doug as well as a change in age to 12½ years old. It also brought a new haircut for Patti, more money for Roger, Connie lost weight, and much more including a change of clothes for everyone (not to mention a brand new middle school).
The Pebbles and Bamm-Bamm Show - ran from September 11, 1971 to September 2, 1972 on CBS, was a television spin-off of The Flintstones. It was produced by Hanna-Barbera Productions. The show followed neighbors Pebbles Flintstone and Bamm Bamm Rubble in their teenage years. The episodes were set mainly in the duo's activities at Bedrock High School, in the prehistoric town of Bedrock. The cast of characters included Pebbles (voice provided by Sally Struthers) and Bamm Bamm (Jay North); their friends Moonrock (Lenny Weinrib), Fabian (Carl Esser), Penny (Mitzi McCall), Cindy (Gay Hartwig) and Wiggy (Gay Hartwig).
Sabrina's Secret Life - originally aired in syndication in 2003 as a spinoff of Sabrina, the Animated Series. In this series, Sabrina Spellman is a teenager (though a year or two younger than her original comic version) attending Greendale High School. Chloe has moved away, and Gem Stone attends a private school far away from Greendale. Sabrina's new best friends are two girls named Maritza and Nicole; additionally, Sabrina still has a crush on her friend, Harvey Kinkle.
Naruto: Shippūden - The second series of the anime Naruto. Takes place after Naruto's two and a half year trainging session with Jiraya. The characters are all 15 years old now except for Neji, Tenten, and Rock Lee who are a year older than the rest of the original group of 12 genin, and the jounin and chunin from the first series such as Iruka, Kakashi, Kurenai,and Asuma along with others whose ages vary.
Death Note - When Near and Mello are introduced in episode 27 it states that a few years have passed since L's death in the previous episode meaning they are all a few years older than previously shown.