Select the events you want to redo. This selects the source for each event (or one source for many events). In the Source Audio menu choose Clear Selected. This deletes all the selected sources but leaves the EDL events in place. Now select the events you want to create sources for and choose Create Sources in EDL menu. If you want to create sources again for the entire EDL, choose Select All Events in the EDL menu and choose Clear Selected in the Source Audio menu. Now select all the events in the EDL and choose Create Sources in the EDL menu.