Clicking on the "Start Again" button didn't work for me today, but replacing the last portion of the URL worked just fine and I was able to retrieve the information that I had filled in the application.
BTW I got the request to complete the below things after about a year of waiting to hear back from IRCC. What does this really mean? Why should I submit the same details again in a separate format?
Schedule A: A separate and newly completed Schedule A Background Declaration form (IMM 5669) bearing an original signature
Travel History Info Form: Information on your previous travel history (trip duration and purpose) including citizenship and resident document information.