I don't think that what you're doing is terribly ethical (although at the same time, I understand the premise that they changed the program without warning), but here is some info that may help.

Virtually all Amtrak tickets (with the exception of Weekly Specials, some rare fare sales, and a very few tickets bought with certain promotion codes) are fully cancelable, whether booked online or via phone.

However, you will only get 100% of your money back if the tickets have not been printed. In other words, as long as they stay fully in electronic form, you can get a 100% refund. Once the ticket has been issued on physical card stock, you can either get 100% of its value back in the form of an exchange voucher or you can get a 90% refund. Tickets are printed one of four ways: by a ticket agent at an Amtrak station, by a Quik-Trak machine at an Amtrak station, by a travel agent, or by Amtrak mailing the ticket to you. Note that you will be forced to choose that last option if your originating station is not a staffed station (PHL, if that's where you're starting from, is staffed, so you wouldn't have to worry about that).

From a cents-per-mile standpoint, it can be a much better redemption rate for AGR points to use them for Amtrak travel--specifically for travel in sleeping class on a cross-country adventure. Have you looked into this? It's a wonderful way to spend a vacation. I'm sure others here would be able to help you plan a trip out that works for your interests and point balances if you'd like.