In your advanced class, what kind of textbook do you use? Most school adopts (unexciting and outdated) textbooks for reading with some questions about context of passages and grammar.
It's difficult to improve speaking skill by such textbooks because you need more communication and interactive practices in class.
「ブラッシュアップ日本語会話 」is an ideal textbook for advanced level students (those who have passed JLPT N1) to improve speaking skill. If you have a good friend to practise Japanese with, this textbook is a good choice.