If I understand you correctly, I suspect that some other issues might be involved other than her not receiving and/or responding to the transfer email.
Under the newer ICANN rules, after 5 days, if the registered contact does not respond denying the transfer, the transfer should go through. As you say this transfer “failed”, I suggest that maybe she currently has the domain on “locked” status with her registrar. That is done to prevent her losing the domain in exactly the circumstances you describe (she didn’t get the email to object to the transfer) by causing the transfer to fail even if she does not object.
I suggest contacting her to make sure that the domain is “unlocked” and her current address is now correct with her registrar and then just re-submitting the transfer request.
You should not have to pay again, because AFAIK, you are only charged for successful transfers - payment information is collected but I don’t believe it is actually charged until the transfer succeeds.
It never hurts, of course, to discuss all this with Support by filing a Support Request, as they may have other instructions and/or information. Good Luck!
*Edit - Scott’s answer says essentially the same thing (typing at the same time?), but he says it better - “what he said” is the way to go!