Curb exclamation points?! I think not!
[By the way, one of my daughter's elementary teachers used to call them "excite marks." We still have a good chuckle about that one.]
Anyhoo, my experience is that in picture books, punctuation is non-standard much of the time. Elipses for page turns, missing commas in lists, etc. And that's fine. In chapter books, I think the punctuation is more standard, depending on the age of the intended audience.
However, I agree that simplicity is best. So instead of a semicolon, can you simply end the sentence and begin a new one? If so, do it.
But limit the use of excite marks? I think not!!