Powerpuff Girls getting a revival starting next year and to celebrate the occasion, Cartoon Network wanted nothing to do with the original voice actresses. The show's creator is also not involved but he gave his approval for the reboot.
Only the Narrator/Mayor's and MoJo's voice actors were confirmed as returning from the original series. Ms Keen's voice actress as well.
http://www.ign.com/articles/2015/06/...f-girls-series