As always, practice is key. But with a higher level, there are more options available to reinforce your language skills. One great way is to simply read a Spanish news article each day. Take time to review vocabulary that you don't understand, and you can choose topics accordingly. I recommend that you visit BBC Mundo for a simple, quick Spanish fix! You may have to provide commentary on a film in the exam. As such, a good way to practice is to watch Spanish films with english subtitles. If you want to concentrate more on the reading side of things, you can add Spanish subs to an English speaking film as well. Don't get disheartened if you don't understand things - Rome wasn't built in a day: it takes time to build up your knowledge of a language! Other than this, it can be a good idea to practice with friends outside of class to reinforce your speaking and listening skillset.