buy more books and manipulatives that support the curriculum for your grade. Sometimes the grade level agrees to compile all the money and buy class sets of books to share. What about a whole year's worth of great read-alouds appropriate for your grade level?
If you have enough books (ha-ha), look around your room and think about what would really make your day easier. Have you found yourself wishing for anything recently? Brainstorm a list and order from most needed to least needed. Look around other teachers' rooms and see if they have anything that would enhance your classroom, too. Order that. Think about what you'll be doing in the next 3-4 months. Are there things that will help with your curriculum? There's always something that you could use.