 This phase II trial is studying how well rituximab together with ifosfamide, carboplatin, and etoposide works in treating young patients with recurrent or refractory non-Hodgkins lymphoma or acute lymphoblastic leukemia. Chemotherapy drugs, such as ifosfamide, carboplatin, and etoposide, work in different ways to stop cancer cells from dividing so they stop growing or die. Monoclonal antibodies such as rituximab can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. Combining ifosfamide, carboplatin, and etoposide with rituximab may kill more cancer cells. 