No you can't. Think of the Earport shops at the airport as a fancy TDS. In order to upgrade it must be handled by a Guest Relations location.
By the way, Epcot is always open until at least 9 pm and you can do the upgrade at either Guest Relations (front gate or International Gateway) there. And as momofmikey mentioned, DTD Guest Relations are both open until 11 pm Sun-Thurs and 11:30 pm Fri & Sat.