Ji has struggled since scoring the winner against Manchester City last season.
"It's been tough for him," admitted the Sunderland boss. "Maybe he thought that goal would be lift-off time but he has found it difficult to cope with the physical aspects.
"I have to realise how young and how far away from home he is, but I hope he has the makings of a player. If there was a possibility of a loan spell I will give it some consideration."