According to the USDA, thawed meat can be refrozen as long as it still has ice crystals on it or it has been kept consistently at 40 degrees Fahrenheit or lower. Refreezing may affect the quality of the meat.
Fish, shellfish and breaded seafood products suffer from some texture and flavor loss if they are refrozen. Most other types of meat, including beef, veal, poultry and meat-based casseroles, do not suffer from texture or flavor loss. If the thawed meat has been held above 40 degrees Fahrenheit for more than two hours, it needs to be discarded. Odor and appearance are not reliable indicators as to a food's safety.