QPR are looking to arrange another loan move for Conor Masterson.
But his time at the County Ground was cut short by a hamstring tear after he had made just five appearances for the Robins.
He has now recovered and Rangers are keen for him to play more first-team football.
Masterson has impressed when he has featured for QPR’s first team.
He has made 16 Championship appearances since arriving two years ago after being released by Liverpool.
However, he had not played any senior football prior to that move and Warburton has long believed that the Republic of Ireland Under-21 international needs a spell of regular game time.
Warburton has plenty options at centre-back, particularly after recently signing Jimmy Dunne, so Masterson is set to move elsewhere before the start of the new season.
So too is another centre-back, Joe Gubbins, who was on loan at non-League Oxford City last season.
Midfielder Faysal Bettache and forward Ody Alfa are also among the QPR youngsters being lined up for loan moves.
Shrimpers look at Karbo
Meanwhile, teenage striker Hamzad Karbo is training with Southend United ahead of a possible loan move to the Essex club.
Shrimpers boss Phil Brown told the Southend Echo that Karbo, 19, has been recommended to him by Rangers director of football Les Ferdinand.
“Hamzad has come in to train and he will play in the first two or three pre-season games we have coming up too,” said Brown.
“He’s six foot four inches tall and he’s been recommended to us by Les Ferdinand and a club we have a good relationship with. We will be having a good look at him.”
Karbo scored for QPR’s development side in a friendly at Hampton & Richmond on Saturday.