This seems like a good thread for this question:

On 7/11/23, I booked a HND-LHR reward flight on 26/10/24 but I now have plans in Japan up to and including 9/11/24. I think that would be 368 days after the date of booking.

Business award availability on/around 9/11/24 is currently zippo but I have noticed on Seatspy that both business and PE seats are often released for HND-LHR flights departing within the following several days.

Would voluntarily changing the flight date on say 24/10/24 (assuming there's availability on a later date) trigger a reissue of the ticket and allow me to change the date to on/around 9/11/24 if any seats do appear? I'd have to eat the £35 change fee each time of course and that may be for nothing if a seat on a flight that suits doesn't appear.

If it makes any difference my outbound flight from LHR-HND is on a separate booking and I'm not aware that they are linked except for the fact that BA customer support applied the 241 voucher used on the LHR-HND flight to the HND-LHR flight when asked on Twitter.