How can I repeat a slide continiously untill I click?

Slides can't be set to loop, only the complete presentation can loop.

The work around is to add a video to slide 1 set to loop:

create a two slide presentation, add the objects and animations to slide 1

set a transition to automatically move to slide 2

export this as a Quicktime file using Custom settings for Prorez

in a new presentation, add the video to slide 1

select the video on the slide and set the video to loop (Inspector > Format > Movie > Repeat: Loop)

add the additional slides