It's been a while since you came to preschool last.
It's been a while since you went to preschool last.
「今日は久しぶりの保育園だね!」は、
保育園では
It's been a while since you came to preschool last.
It's been a while 久しぶりだね
since you came to preschool last あなたが最後に保育園に来てから
家では、
It's been a while since you went to preschool last.
It's been a while 久しぶりだね
since you went to preschool last あなたが最後に保育園に行ってから
が、言いやすいと思います。