Saving game timer?

When I load my script, time starts from zero. How do I save my game timer?

Here is my script:

public float seconds, minutes, hours;
public Text levelTimer;
public float GameTime;

// Update is called once per frame
void Update () 
{
    hours = (int)(GameTime / 3600.0f);
    minutes = (int)(GameTime / 60f);
    seconds = (int)(GameTime % 60f);

    levelTimer.text = hours.ToString("00") + ":" +
            minutes.ToString("00") + ":" + seconds.ToString("00");
    GameTime += Time.deltaTime;
}

public void save()
{
    PlayerPrefs.SetFloat("second1",seconds);
    PlayerPrefs.SetFloat("mins1",minutes);
    PlayerPrefs.SetFloat("hour1",hours);
}

public void load()
{
    seconds = PlayerPrefs.GetFloat("second1");
    minutes = PlayerPrefs.GetFloat("mins1");
    hours = PlayerPrefs.GetFloat("hour1");
}