AutoRepublish is used to save a copy of a part of the Excel file to a webpage everytime you save the file.
What if you want to change the settings?
1) Select "Save As Single File Web Page"
2) Click the button 'Publish'
3) Choose "Previously Published Items" (Use the selectbox left of the button "Choose")
4) It seems you have to click 'Publish' everytime you make a change to make it last. So if you have several areas you want to publish you will have to click a lot.
If you open a file with AutoRepublish setings in Microsoft Excel for MAC and ignore the warning your autorepublish settings will be lost.