From the menu bar you can open the Slideshow settings using the icon. Alternatively, you can also open the dialog via Slideshow -> Slideshow settings. Under End of slideshow you can enable the Repeat current slideshow function.
If you convert your show into a Video-DVD this functionality will be lost. If you create your Video-DVD with SlideShow-Manager you can there activate the repetition of the of replay.
icon. Alternatively, you can also open the dialog via 
