I haven't done this personally, but my reading of https://www.ana.co.jp/en/jp/guide/am...efund/suggests that after making a reservation, you can change it freely to any dates as long as travel is completed within one year of ticket issuance. ANA has no award change fee but is very strict about what constitutes a change vs cancellation; the routing must be identical.

I think you should be able to make a reservation right before your miles expire then freely change it for a year if you already know the route you want. I'd call (or get confirmation from someone else here) to check that. Otherwise,

* Book tickets for a family member (or "cousin", but personally wouldn't mess around with this)
* Skycoins (could be worth getting an ANA card for better rate)