I need more money...can I get the rest that the govt. awarded me?

I took out $3,400 in federal subsidized loans this year, so for this fall semester I received half of that which is $1,700....and this coming spring semester I am supposed to be getting the other half. So, as of now, I am only receiving $3,400 out of the $5,500 that I am eligible for. However, I need the rest of the $2,100 and I was wondering how I should go about getting it. Thanks!