How do I change the framerate of an animation without destroying it?

[Zoey Time]

I have a problem with my animation in photoshop, I started with 30 fps in a video timeline and want to change it to 12 fps, but it kind of destroys the project: the 'insert blank frame' doesn't work like it should anymore (deletes following frames etc.). Is there a way i could fix this? Do I have to change the framerate before I start animating?

[JJMack · Accepted solution]

Are you doing a frame animation or a video animation? And you lost me. If you had 30 fps and want to change it to 12 fps would you not be discarding ever other frame  like every odd frame to get down to 15 fps.