If you plan on creating more than one slideshow using SlideShowPro Player for Lightroom, managing the content and templates used when exporting is an important task. Here's what we recommend for this.
For each slideshow you publish, we recommend creating either a "Collection" or "Folder" in the Library area of Lightroom. Name the folder/collection with a title that's memorable and easy to identify later. Then drag the images you'd like to use with that slideshow from your Library into those folders/collections. This allows you to return later (when exporting an updated slideshow) to add more content, or change your slideshow order, without having to recompile all your images again. Once built, you can choose that folder/collection in the Filmstrip when using SlideShowPro Player for Lightroom.
If you've modified the visual appearance of SlideShowPro using the parameters in the Web panels, chances are you'll want to save them. You can save your settings by creating a template in the "Templates" area in the far left column. We recommend naming the template the same as the folder/collection that it relates to so you can quickly select your content, and the template it belongs to, anytime you need to update content.
You can also read about Web Templates from Adobe's online documentation:
LR2: http://help.adobe.com/en_US/Lightroom/2.0/WSC8DB18E8-337F-46bc-89C5-5F7F7408696C.html
LR3: http://help.adobe.com/en_US/Lightroom/3.0/Using/WSC8DB18E8-337F-46bc-89C5-5F7F7408696C.html