The link should refresh automatically each time the database is opened. You can use the TableDef.RefreshLink Method to update via VBA.
HOWEVER, if all the users have MS access on their PC's, it makes more sense (to me) to just use MS Access. If the data is manually keyed in Excel, then create a new data entry form and get the data keyed directly. If the data is copied/imported into Excel, you can just as easily paste it into MS Access.