Gray left Selhurst Park at the end of last season hoping to join a Premiership club, but Palace could not settle a fee for the winger.
"Julian has been unable to find another club and will return here on a week-to-week contract," said Kember.
"As part of the deal set up when it went to court, we agreed to pay his wages until the end of September.
"Now he'll come back and train with us and we'll see how the situation resolves itself," Kember told BBC Radio London.