Whether you're running a PowerPoint 2013 presentation by hand or playing back a slideshow with recorded timings, set the show to loop continuously to restart it automatically every time it ends. To loop a slideshow once rather than indefinitely, create a custom slide show instead.
Open the Slide Show tab and click Set Up Slide Show.
Check Loop Continuously Until 'Esc' and click OK. When you run the show, the presentation jumps back to the first slide rather than ending after the last slide. To end the show at any point, press Esc.
PowerPoint's custom show feature provides a way to create a show out of any of the presentation's slides, placed in any order. By choosing all of the slides and then repeating the same slides, you effectively create a one-time loop.
Open the Slide Show tab, click Custom Slide Show and choose Custom Shows.
Click New to build a custom show.
Check the boxes by each of the slides in the presentation and press Add to add them to the custom show. Check each of the boxes a second time and press Add again to add the second loop of slides to the show. Click OK when finished, and then click Close on the Custom Shows window.
Click Custom Slide Show and choose your custom show to play it. Playing the presentation normally — by using the From Beginning button or selecting F5 — won't include the custom show's extra loop.