1.Extract InfoPath form
2. Open View.xsl file
3. In the control property put xd:disableEditing="yes"
4. Save the file

XDocument.IsNew

If this property is true it means the form is first time opened.
If false, already submitted form is opened.

open manifest.xsf file in design mode.
Go to File > Save As... and save the file.
It will save the form as .xsn

For doing it programatically use makecab.exe

Visit URL

visit URL

# Unpack XSN file using extract.exe utility to the local temporary directory.
# Find manifest.xsf file and open it as a plain XML file.
# Replace the corresponding URLs using the XML DOM.
# Save the modified manifest.xsf.
# Pack all files into the XSN using makecab.exe utility.
# Clean up your temporary directory.