Originally Posted by number_6
It is your bad luck to have caught the cusp of an increase; you might be able to get the old booking reinstated (but you cannot make any routing changes).
Only if the ticket was actually issued - until that point the price is not confirmed. Once the ticket has been issued then you are locked into the flights up to the first international segment; after you have flown them you would be able to do a reroute/reissue for US$125 without the new price kicking in, but if you want to change the first international segment or any flights before it then you have no choice but a cancellation and reissue at the then prevailing price (but without the US$125 change fee).