Examples:

• That's very generous of you, but I don't think so.
• Answer: Probably, but I don't think so in your special case.
• Thanks for the vote of confidence, but I don't think so.
• I don't think so, but she hired a private investigator.
• I don't think so, he lost interest in the auction early.
• I don't think so, already too high 130 million dollars!
• It could be the accident, but I don't think so.
• I don't think so, but I'm not 100% sure yet.
• I don't think so or have not heard of this.
• I don't think so because not all cultures are represented.