The purpose of this study is to determine whether this disease will get better if treated with higher doses of Lenalidomide even if the disease returns while taking low doses of Lenalidomide. In patients with multiple myeloma treated with Lenalidomide maintenance, the disease will return. However, the physician currently does not know if the disease would respond to treatment with higher doses of Lenalidomide. This is very important for patients with multiple myeloma because the number of drugs available to treat the disease are limited. It is important to know if Lenalidomide remains still effective and if it can still be used in this situation. This study will try to find out what effects, good and/or bad higher doses of Lenalidomide has on the patient and the disease after it has returned.