Sent out Save the Dates but changed the wedding date by a year. How to tell everyone?

We had originally set our wedding date to August 2013, but since I recently moved to the US and can't work for a while, it makes finances a little tough. We both agreed to push it off by a year.

We've dealt with any vendors/services we've already booked, and told our parents, but everyone else is hard to get to.

Do we send out "Oops- don't save that date!" letters out, do we e-mail, call...? I don't know what procedure is here. We're likely going to send out more save the dates later on, closer to our actual wedding date... I just don't want to inundate people with information...

What do you think?