Originally Posted by
YOW_RTW
Yes, the E+ vouchers must be applied to a booking during the year they are valid, the upgraded flight(s) can physically occur upto 350 days later (ie the maximum possible booking window). You should be aware, however, that if you cancel your reservation after the voucher has expired it will not be returned.
...
If there's a schedule change by more than 15 mins you'll be entitled to redeposit the expired voucher with a new expiration date that usually lasts till the end of the year. But please redeposit first by submitting a feedback form and only then after the actual deposit cancel the booking.