Can CPS take my kid if have a closed CPS case?

New kid or old one. New one, probably not unless there is another complaint. Of course if the hospital knows of drug use while pregnant, that might go it. For the old kid, maybe if you haven't complied with their requirements, but again, I would think that a complaint would be necessary first.

Yes. If new grounds, even if they look like the ones from the past are reported, they are obligated to take the child(ren.) I recommend once your case is closed you relocate. You are never sure who reported on it before. Moving helps you and the children make a new start. I presume if went in your favor and the kids were returned. If you had to do services, that is all in your favor.