After you file

Good grief... who designed this forum?  Here's the question I was replying to: 

"Not knowing that I couldn't e-file an amendment - I selected the Amend button for the already sent return.  It allowed me to correct my mistake.  Only at the end did I realize that I couldn't submit it.  My problem is that  now that file has the updates and I no longer have the file of the 1st submission.  There is no other file that has an "amended" extension or anything.  

 What should I do with this file once my return is approved/completed by the IRS and I'm allowed to submit an amendment?  I also looked in Forms just to be sure there wasn't a 1040X in there (no).  I'm not sure how to proceed - should I undo my correction - resave it and then later try to amend it again?

Please advise."
Thanks in advance if anyone has an answer to this!