InfoPath clearing existing information in saved forms in SharePoint list

I created a Form in InfoPath 2013 and published this form to a SharePoint library in Office 365. The form worked great for the first few submits, but we decided to change, or modify the existing fields and here is where we found an issue:

We updated the form with the new/updated fields and after we published again I noticed the new published form cleared the data in existing forms that were submitted before the changes/updates to the form, luckily we capture some of the fields on the SharePoint list and we had that info, but the previous forms have some fields that are empty now.

My question is - If I modify this form, or add more fields, it will clear my existing data? Is there a setting in the SharePoint list, or form that will prevent existing data in the forms from being replaced, or cleared?

Thank you much in advance for any advice!

Mario G.