Since this is a schedule change that will put you in 2 hrs later you should be able to change without a fee. If you do the change over the phone and the agent agrees to this, make sure you get their name so that you have a record of confirming that you don't have to pay a fee. This is because even if you don't change the new routing, you will have to have the ticket reissued before you start travel since the flt #s are different.

The thing to remember is to put off reissuing till the last possible moment since if the trip is months away you can be sure there will be future schedule changes. In fact, I just reissued 4 tkts for Asia this evening that are for travel in a couple of weeks.