You should keep the existing booking "alive" as long as possible (i.e., up to 12 months from the originally booked flight) by not cancelling an existing 280,000 point award itinerary. Instead, make an interim flight booking (just one flight will do) for sometime in the future, replacing all existing flights, and therefore keeping the same PNR. For example, I can see QF domestic award flights currently available as far out as 5/6/21.
All changes (including additions) to your itinerary before 31/10/20 should not incur any change fees. However, cancelling the current award flights and starting all over again will cost 318,000points.
Depending upon how long ago you cancelled the itinerary, you could try contacting the Call Centre to see if the PNR can be kept alive.
Also, following cancellation, all QFF points will be returned to your FF account and the taxes will (at some point) be recredited to your credit card.
Edit: My understanding is that cancellation of both old and new award bookings have no change fees until 31/10/20. However, someone else may have better information on this