 This phase III trial studies the side effects and best dose of lenalidomide when given after combination chemotherapy with or without rituximab and stem cell transplant and to see how well it works in treating patients with persistent or recurrent non-Hodgkin lymphoma that is resistant to chemotherapy. Biological therapies, such as lenalidomide, may stimulate the immune system in different ways and stop cancer cells from growing. Drugs used in chemotherapy, such as carmustine, etoposide, cytarabine, and melphalan, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Monoclonal antibodies, such as rituximab, can block cancer growth in different ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and help kill them or carry cancer-killing substances to them. 