How can I improve my novel idea?

There is no need to improve it just write it. You have all the ingredients for a good story and I have to say that there is just a little of Logan's Run about it even if the age and intelligence requirements are different. If you don't have an ending don't worry because that will come to you as you write the story. As for improvement - not necessary - why try to fix something if it is not broken. Good luck with your story.