I don't believe that you have lost the barcode.
Either the Pektron accepted it, in which case:-
A: it is waiting for the matching fob to be used
B: if you enter it again I think that it will refuse it, because it's already been entered.
Or
It didn't accept it, in which case you can just enter it again.
The codes are only one time use in the sense that the written code matches a fob until the fob code rolls out of the window and the code changes. Unless you press the fob buttons dozens of times, the code is still valid. So only a new code and fob can be used, but, they remain new for a while, not just once.
I hope I've explained that well, I'm not sure I have ...
Watch the YouTube video that I made and you will see that I ran into similar problems, but in the end it did work.
I think that what you should do is to start the process again, with the 22 digit code that you already entered. If you get an error then that means that the code is already in the Pektron so just carry on regardless.