Randomized phase III trial to compare the effectiveness of interleukin-2 with that of observation following radiation therapy, combination chemotherapy, and peripheral stem cell transplantation in treating patients who have refractory or relapsed non-Hodgkin's lymphoma. Interleukin-2 may stimulate a person's white blood cells to kill non-Hodgkin's lymphoma cells. Giving interleukin-2 after radiation therapy, chemotherapy, and peripheral stem cell transplantation may kill more cancer cells