I found and I read in Wikipedia about Kelly and it says:

"In 2009, Sheridan had been reported by Mattel to change their direction of Barbie into a new way of more modern and much fashionable products including the films. It also affects the voice dubbed line in which Mattel makes Barbie much younger including her voice. So in 2010, after Sheridan has her last voice in Barbie in A Mermaid Tale as Merliah Summers, she's been replaced by Diana Kaarina in the film Barbie: A Fashion Fairytale and all other upcoming films such as Barbie: A Fairy Secret."