Check out this. I think it will help you

http://infopathdev.com/forums/topic.asp?TOPIC_ID=1577

The easiest and most straightforward solution would be to publish it
to a new form library....maybe you could group the related libraries
together on a subsite with versioning included as part of the form
library name whenever you change the xml schema.

eg:
http://abc.com/sites/HR-Forms/PA112
http://abc.com/sites/HR-Forms/PA112-v1
http://abc.com/sites/HR-Forms/PA112-v2
http://abc.com/sites/HR-Forms/PA112-v3
http://abc.com/sites/HR-Forms/PA112-v4

It would be very simple to do this, and the form would even "remember"
what fields are published in what order for the Sharepoint columns
when you go to republish it to a new location. If you have a number of
custom Sharepoint views of the formlib's data that you want to
preserve, you could save the original as a template,  create the new
(latest version) form library using that template, and then publish
the newest form to it....

I haven't tried this, but if you wanted to preserve the particular
original url, you should be able to rename the pre-existing form
library to add versioning info (eg above) and then create the new form
library with the original name.