If you know where the files are (which content directory they are in) then find the Default Lights and Shaders in the Content Library pane's product listing, right-click on one of the files, and click Database>Edit Base Paths, then in the dialogue set the Change option to All Files Using This Path (if you've moved everything to the same location - if not select all the files in the product folder before right-clicking and leave the Change option at Selected Files), then for Change To pick the right content directory.

Connect, in the 4.9 beta, does use relative paths only so if you use that when it goes live (or in the beta) this should not need doing in future if you move the content to a different content directory.