Hi,
1. Can you verify below steps.
- Open form in design mode.
- Select Tools à Resource Files.
- Click on add button and select your xml file.
- Select “Replace the existing file” option.
- Click on ok.
Note: Make sure your new xml file and already added xml file name should be same.
2. Otherwise extract you template into one folder. Now replace your new “customers.xml” file fin the extracted folder. In this way you will see the newly added values in the infopath form.
If you want to add any new values, then update your xml file in the extracted folder. It is the better way to update the Resource file from Extracted folder.