How do I reset "All Imags?"

I have this folder structure as I did in LR. One sad thing with C1 is I can't enable or disable showing all photos with sub-directories as I can in LR.

So ok, "All images" or the one it auto adds on import for "untitled". Thing is I would like it to scan all of the directories again and add, remove what it did on import. There are times it gets out of sync and shows the ! triangle thing in film-strip.