The Railwaymen's slide into the bottom tier was confirmed earlier this month and Thordarson is already making plans to reshape his squad.
He told the club's official website: "The priority remains a centre-half and a central midfield player.
"I would like to add some experience to the squad. Even if we can add one or two defenders and a central midfield player that doesn't mean it is the end of the changes.
"There could be more, but I have to make sure the signings are right."