I think that this moment is supposed to tell us that Carol Anne finally realizes that the ghosts are not her friends. She views the paranormal activity in her home as a game before she is taken, and probably does not know that the same people are responsible for her forced relocation. It's possible that she makes the discovery in this scene, though. Carol Anne might mean that there is going to be no more fun.
shareI think she already realized it at that point. This is after she came back from the other side. Everyone thought it was over. I thought her no more statement was "I can take any more of this".
shareThank you, WandererFromYs. What Carol Anne says in that time is in the form of a question, not a statement. She is emotionally fine after being rescued because her passage back to Earth resets her normal life, but the effect is temporary. The girl watching her room being destroyed restores her feelings of danger even if she can't name the source, and she recalls her original connection to the ghosts. The look on Carol Anne's face suggests that she is combining the two.
shareI think it's a statement, not a question. She's almost begging "no more" like "I don't want any more of this".
It's a sentence fragment, so it's open to interpretation, but I can't really resolve it as being a question, and it being negative, which would fit the scene. Your suggestion of "no more fun?' Would be a positive. Meaning she is asking for fun. But in the context of the scene, it seems to clear to me that she doesn't want it.
Also I checked the script to see how its phrased there, and that lines isn't in the script, so I guess it's open to our interpretation.