Brian, this is normally something CAD asks you in a little bubble at the bottom right corning of the window. It'll notice when an xref has been saved while you were working and asks if you want to reload it right then. You click yes and it reloads.

You should be able to select multiple xrefs in your manager to reload them all. If not, it might be because the xrefs are actually nested. I prefer to not allow nested xrefs when I can, because of these control quirks.

Otherwise the fastest way is to close (and save) your drawing and then reopen it if you have a lot of xrefs needing reloading. Xrefs load as their latest version when you open a drawing.

-Amanda