What do you mean? The learning rate is usually not updated automatically.
You can adjust the learning rate with e.g.:
def adjust_learning_rate(optimizer, epoch):
    """Sets the learning rate to the initial LR decayed by 10 every 30 epochs"""
    lr = args.lr * (0.1 ** (epoch // 30))
    for param_group in optimizer.param_groups:
        param_group['lr'] = lr

or with optim.lr_scheduler.