"overlooking the fact that I will lose all data from the previously
created documents already stored in the library"
You have Infopath (filled with data fields) forms as .XML files. You probably cannot open them with new Infopath template though it should not have happened, the old XML forms should have referenced and opened by the reference to the previous/old template (with which they were created). Here is the opposite question: how to open old Infopath XML data forms with a new XSN template
First, to ease treating such issues in future I propose to enable versioning in Vesrsioning settings of Form Liobrary settings or better save your templates locally under different names on each publish with some bookkeeping records. Note this is different from Infopath form versioning set by default to "Automatically update the template (recommended)"
Please check 3 methods of relinking Infopath data forms XML files to XSN templates
First, you should regain treating, i.e. opening your XML files through Infopath without trying to tweak it manually. And if you try, don't forget to backup all
You can try to tweak/edit and open Infopath (.XML files) data forms in Excel or better to export to Excel from Infopath Designer 2010:
on ribbon File > Save & Send > Export to Excel (Export form data to an Excel Workbook )
- Export data from single or multiple forms
- Use Excel to analyze data
that launch Export to Excel Wizard.
Vice versa, In Infopath Designer 2010, File > New > Convert Existing Form
- Creates a new form template based on either a Word or Excel file. InfoPath creates the underlying data structure based on the layout of the original form, updating the data
structure based on any changes you then make to the form
permits to import Excel workbook into Infopath form
I am on Sharepoint Online aka Office365 (can't check much in other Sharepoint environments) ) in which I can leverage Excel Services