Hi Jeff. I am sorry to hear that your work in Survey123 designer was lost.
Understanding the issue you run into in more detail would help us diagnose the problem and potentially fix it, so others -or yourself- will not run into it again in the future. If you have more details and would like to share them, please open an Esri Technical Support incident so an Esri analyst can go with you through the process and document it for the Esri development team to fix issues found.
From your description above, it looks like you are changing the choice lists in your XLSForm but your feature service domains remain the same after publishing. This is expected, because the geodatabase domains are created when you publish the survey for the first time. Survey123 Connect does not update your feature service domains when you publish the survey. This is how the software is designed at the moment.
I found this idea in GeoNet https://community.esri.com/ideas/17261 you may want to have a look and vote if you agree with it.
Generally, it is not a good idea to re-publish a survey authored in designer with Connect, particularly when you make schema changes. It is best to download the designer survey in Connect, make a copy of it, publish the copy as a new survey and delete the original designer survey to avoid confusion. When you publish the survey for the first time from Connect, your choices in the XLSForm will be converted into a geodatabase domain. Again, once that domain is created Connect will no longer touch the domain, even if you change the list in XLSForm.
