The 36-year-old is entering the final year of his current deal and he has warned he could leave for free next summer if the club do not secure his future.
Schwarzer: "We haven't spoken about a new deal yet and, while I'm extremely happy at a club that's given me a new lease on life, there is a possibility I could move on a free transfer at the end of my contract," Schwarzer told The World Game.
"I haven't ruled anything in or out. My main priority right now is to push through to the next World Cup.
"If I'm still on top of my game and enjoying things, then of course I will look to continue at the top level for at least another year beyond that."