If it is within 24 hours of when you booked, you could just cancel for a full refund. Probably not the answer you want to hear, but might be worth looking into.

Years ago, when I was a US CP (similar to AA EXP), I would call and speak with an agent to ensure there were upgrade opportunities on flights before booking. They would book for me, then immediately upgrade me. Might be worth calling when you see that system-wide upgrades are available to just call first, maybe book (while on the phone) after the agent verifies, then upgrade.