Thanks very much for the replies!

I read that thread, and it helped, but wow is it ever confusing. The information definitely conflicts and everyone seems to disagree with each other. Why oh why doesn't AA just use travelbank...

What I gathered is:
1) If you book before the expiry (one year after the original booking) they may or may not allow you to ticket a flight after the expiry. Official policy says they won't do this. It appears travel must commence before the original date of booking, so people who got around this were lucky.
2) there may be a way to extend the credit by booking a refundable or non-refundable ticket

So assuming I can't just ticket the flight after the expiry date, it looks like my options are:

1) Book the cheapest refundable flight I can find, immediately cancel it, and then hope that the new ticket number or a voucher will allow for a re-ticket for another year. I assume this would cause 2 tickets/vouchers to be issued (one for the remaining residual funds, and one for the cancelled refundable flight). Hopefully, both of these would extend the expiry. I'm thinking it may be best to try to find a refundable flight that is exactly the same amount as the value of my cancelled ticket to avoid having two credits.

2) Book the cheapest domestic throwaway non-refundable ticket that commences before the expiry date, and be issued a voucher for the difference. This voucher may work past the original expiry date. There was talk that you may have to attend in person at the airport to do this, but this is really difficult for me (nearest AA-served airport is 2.5 hours away). There was also talk that if you no-show or cancel the new flight, you won't get issued a voucher.

It appears there is some risk that one or both of these options may not work at all and the original expiry will apply.

Can anyone chime in on any experiences or thoughts with either option?

Thanks again for all the assistance.