You could maybe try and think of different areas where knowing some basic phrases would be useful such as shopping. Create a list of common phrases, teach them about how the money works from your country, and then create a "game"/simulation where the students are using and practicing the phrases and ideas. I know that you are not suppose to play games, but you could always argue or tell your principal that you have created a practicle/real situation where they would use the conversation english that you taught them and that it will help them further their retention.
Just think of all the different times that you have been out and about here in Korea when you first got here and wished that you knew more of the language than you did, and then use those situations for your convo. classes/camp.
Maybe create a small "shopping mall" where some students are customers and others are the workers, and the workers as the customers if they need help finding anything, answering any questions "How much is this? Is there a sale?" etc. and obviously not giving them too much depending on their skill level.
Another idea is maybe "recreating" a restaurant with basic phrases there.
The possibilities are endless! I hope this helps you, and best of luck to you! I am in a similar situation with Middle school, but I am not allowed to use shopping, so I am thinking about maybe doing the restaurant idea OR a summer olympics theme since those are coming up this year!
