For repeating tables:
Open "Repeating Table Properties" -> Click "Customize Commands..." -> in the action window click the down arrow and select "Insert Above" -> check the "Shortcut Menu" option
The only catch to this is that you have to "add" using the shortcut menu that pops up to the left of the table
For repeating section:
Open the "Repeating Section Properties" -> Click on "Modify" on the repeating group -> Click "Customize Commands" -> in the action window click the down arrow and select "Insert Above" -> check the "Shortcut Menu" option.
Again the catch is you have to use the shorcut menu that pops up when you click within the section.