If I book a flight for X points on the outbound and Y points on the return and the price of the flight goes down, how do I get a refund of the difference? Some say "cancel and rebook" but I have also purchased an E+ upgrade on these flights. If I cancel, do I lose my E+ upgrade, or does the money for the E+ upgrade go into travel funds.

I went in to do a change of a flight I recently booked and the system says "not available" for the flight I booked. It appears that I could book a different time that same day, which if I completed that transaction, I could then go and change again, back to my original flight and through that process, get a net refund of points.

Any tips would be appreciated!