I ran into a problem using Maps for Office. I successfully loaded up a map with 2 features on it into AGOL. For some reason the map on AGOL wouldn't load. Assuming it was because of strange characters in the naming of the features, I deleted the feature services and the map from AGOL.
Now, whenever I open the Excel file, the map just says "Update Map" and "Update Layer". Since it was deleted on AGOL, if I hit either "Update" button, it fails.
As to the "idea", I'd suggest that the add-in, upon loading, should check to see that any layers or maps in the Excel project actually still exist in AGOL and update the buttons' functionality accordingly.
As an alternative, enable the add-in to use the same map to create a NEW map and/or NEW features even though they've already been shared up previously