Book an award ticket for 11.9 months from today. Any award ticket. You can't refund the miles to your account but you can use them as credit towards another award ticket if you subsequently change your mind about the initial flight.

That's how it works for Diamonds anyway - maybe they are not so flexible for others.

Alternatively find a friend who needs an award for whom you can get a ticket and they can return the favour later (or make some other consideration).