To link media the new files have to be at a folder further upstream from the old data.  1. Move the old media location to some different folder, preferably to another drive.  2. If it hasn't been done automaticaly, select all clips and right click to "make offline" 3. Select all media, right click to "link media" 4. Tick "relink others automatically" 5. Find one of the files that you want to link