Adding another row doesn't require a building block. For a basic table, all you need do is click on the table and choose Table Tools|Layout>Insert Above or Table Tools|Layout>Insert Below.
If you want to replicate a table row containing content controls before the last row in a table, see, for example:
https://www.msofficeforums.com/word-...html#post87989
https://www.msofficeforums.com/word-...html#post38461
https://www.msofficeforums.com/word-...tml#post145675
Beyond that, it's impossible to code for something as vague as "updates the data in rows".