The 22-year-old made 14 appearances for the Bluebirds, who won promotion from the Championship last term, during a loan spell in the second half of the season.
Although Warnock stated earlier this week that he would not "wait forever" for another move to materialise, the 69-year-old remains eager to recruit the Serbia international once again.
"I'm always optimistic," Warnock told Sky Sports News after Friday night's 1-1 friendly at Torquay United. "You've got to be at my age.
"We were a bit thin on the ground [in midfield] against Torquay in that area without Aron Gunnarson as well so it shows we've got to make sure we get somebody in, in that position."
Cardiff get their Premier League campaign underway against Bournemouth on August 11.