McGhee told the club's official website: "I think Kevin has done quite well but at Burnley he did particularly well and obviously that performance at Turf Moor is what we hope we can get out of him every game.
"I think he showed there what a good player he could be for us. He got his goal on Saturday at Coventry and he contributed to a fine win. He's proven that he is worth having around for a bit longer.
"He needs more games and he will get stronger, but he has scored twice in four games which is good going."
Meanwhile, winger Steven Reid is poised to return to training after suffering an ankle injury during pre-season.