Yes, but don't forget to rest and relax! You need the balance between the two. I suggest revising over everything, but not in too much detail since you won't have enough time, but not in too little detail that you don't know enough.
Practice questions in Maths, Write out Vocab in Spanish (maybe create flashcards) and for everything else, get a good revision guide and read through it, highlighting key points!
Relax - 4 weeks = 28 days = 672 hours! There's only 1440 hours in a school year, so in theory, you can do it!
Best of Luck!