Good news! You don’t! In the MLS menu under Listings is the Copy Listing tool. Click on that and simply enter the listing number of your prior listing, click Next, and follow the screen instructions; the default setting is to keep the new entry under the same listing type as before. A note that you must still be with the same brokerage as the earlier listing for this option to be available for you.
If you have any questions, please contact MLS Support at mls@sfrealtors.com!