The defender is off contract in June.
Clarke said: "I have given thought to it. It's an ongoing situation. I said earlier in the week that the last six games won't change the situation for any player at the club.
"I am comfortable in my own mind where I'm going but we won't make that decision until the end of the season and nobody will know until then. I haven't sat down or had long conversations with him but I know Goran is happy here.
"He is happy with the work that he gets and the only thing he's unhappy about is that he hasn't had more minutes on the pitch. He was in the team but he lost it due to an unfortunate incident."
Clarke continued: "I'm happy with him. He's done well and been a good addition to the squad.
"But I don't socialise with him so I don't know how he well he has settled in but I see him day in, day out, and he seems comfortable. The boys like him, he's a good character and he seems comfortable in England.
"We will sit down and have that final conversation around the end of the season."