If you have clicked the "generate note" button on the SOAP notes screen, and decide that you want to go back to that screen revise what you have entered, first get back to the regular "HIPAA-style" notes screen where the generated note is displayed. (You may be there already; if not, click the "chart" button on the daily schedule to get there.)
Now here is the counter-intuitive part. Click the button at the top that says, "Erase this note and start over." This will allow the SOAP notes button to be displayed again. Now you can click the SOAP notes button, where you will find all of your previously entered selections and notes intact.
Of course, don't try this unless it is a SOAP note; if you do it for a regular note, it will, as promised, erase the note to let you start over. SOAP notes are stored separately and are updated each time you click the "generate notes" button; this is why it is safe to erase the generated note.