your doctor might have suggested you repeat cesarean section because of some recurrent indication.
after 38 completed weeks the baby will achieve sufficient maturity to survive outside the uterus
normally repeat cesarean section will be planned one week earlier to avoid onset on labor pains which may lead to uterine scar dehiscence etc.
the suggestion of early cesarean might also be because of some other problems in continuation of pregnancy
-high blood pressure
-macrosomic baby etc.
so you better follow the advice of your doctor.