Jol has managed to persuade Fulham stalwarts Brede Hangeland, Damien Duff and Philippe Senderos to sign new contracts, but Schwarzer has yet to extend his deal beyond this summer.
The 40-year-old remains Jol's first choice, but the Cottagers boss needs to bring in new back-up as David Stockdale and Neil Etheridge are not happy to stay as understudies.
"I don't deny that we are looking for a goalkeeper," Jol said. "There is a lot of speculation in the press. I have a young goalkeeper in Neil Etheridge, he is out on loan, and so is David Stockdale.
"He doesn't want to be number two so that could be a little problem, so of course we are always looking for a goalkeeper," added Jol, who is confident of talking Schwarzer into a new deal.
"We are talking to Mark Schwarzer like we did with Brede and the other players," he said. "He is a fantastic goalkeeper so you would have to be very good to fill that space.
"We have made him an offer so we are waiting. If he accepts he will stay, if not we will talk again like we did with Brede."
Jol also says he is not concerned that Dimitar Berbatov's scoring exploits will lead to a flurry of offers for the forward this summer.
Berbatov took his tally to six in his last six games on Monday night as Fulham moved to within one draw of the 40-point mark with a 3-2 win over local rivals QPR and Jol appears to have pulled off one of the deals of the season by signing him from Manchester United.
"Last year I lost Bobby Zamora and then Pavel Pogrebnyak came in and scored a lot so there always is a solution if something happens, but you want to keep your best players," said Jol, who brought the best out of Berbatov during a prolific two-year spell for the Bulgarian at Spurs.
"Dimitar is 32 and I think he is happy here. I can see him stopping here for the next two or three years."