The series is being extensively "refreshed" for Japanese TV. It is not new animation, but simply a remastering of the original film. Part of this will be reformatting and extending the picture to 16:9 Widescreen (the Jump image says it will not be a cropping of the series, at least not completely). Through digital processing, the image will be made vibrant. All the grime, damage and noise remaining on the "Z" film will be removed, making the image much clearer in HD.
Dragon Ball Kai will include a complete re-recording of the dialog by most of the original Japanese voice cast, as well as completely new sound design with updated sound effects. The opening and ending themes are completely new, having nothing to do with the original themes. Takayoshi Tanimoto performs the series' new opening and closing themes, "Dragon Soul" and "Yeah! Break! Care Break!".