It may not feel like it now, but what you have in your head is a very, very strong foundation on which to build a functional understanding of Chinese language that is unparalleled among all but the very best Chinese students of your generation.
Why let that slip?

While you may feel some burn-out from a semester of tests, presentations, and daily quizzes, you will regret it if you put Chinese out of your mind for the whole break.
Follow any advice your instructor gives you for maintaining your language.
Using our Quizlet flashcards is a good idea. Go back over old sets and star only the items that you may forget over time (though not necessarily the most obscure characters). Adjust the settings to only quiz you on starred items, and pare them down until you know them all.

REMEMBER: there are sentence flashcards, too, which could be a more interesting way to identify words and grammar items that may be fading from your memory. Just use the cards that start with Chinese characters, and turn the sound on. Don’t look at the cards as you flip between them; just let the Chinese play and see if you know exactly what’s being said. Eliminate the easy sentences so that you can hear the most useful ones at the highest possible frequency.