RATIONALE: Drugs used in chemotherapy, such as clofarabine and cytarabine, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Colony-stimulating factors, such as G-CSF, may increase the number of immune cells found in bone marrow or in peripheral blood and may help the immune system recover from the side effects of chemotherapy. Giving clofarabine and cytarabine together with G-CSF may kill more cancer cells.