Quick question about restarting levels on fail

Hi guys. I got a quick question for you. I have already everything prepared. I am making a simple launching game, where you need to kill all enemies to pass to the next level. I have 2 methods GoToNextLevel()
and AllMonsterDied(); . Need to make something like with if statement like if

(! allMonestersDied)
{
restart level
}

public class LevelController : MonoBehaviour
{
    [SerializeField] string _nextLevelName;
    


    Monster[] _monsters;

   
   
        void OnEnable()
    {
        _monsters = FindObjectsOfType<Monster>();
    }

    
    
    
    
    void Update()
    {
        int currentLevel = SceneManager.GetActiveScene().buildIndex;

        if (currentLevel >= PlayerPrefs.GetInt("levelsUnlocked"))
        {
            PlayerPrefs.SetInt("levelsUnlocked", currentLevel + 1);
        }

        if (MonsterAreAllDead() )
        {
            
            GoToNextLevel();
        
            
        }
       

        Debug.Log("Level" + PlayerPrefs.GetInt("levelsUnlocked") + "UNLOCKED");
      

    }


    

    void GoToNextLevel()
    {
        Debug.Log("Go to next level" + _nextLevelName);
        SceneManager.LoadScene(_nextLevelName);

        
    }
   

    bool MonsterAreAllDead()
    {

        foreach (var monster in _monsters)
        {
            if (monster.gameObject.activeSelf)
                return false;
           
        }

        return true;
    }

    




}

but need that happens after 3 times fail to kill all monsters and some icons in-game which is connected and show number of attempts left.

If needed I will post the whole code of methods.

Thanks a lot. <3

Anyone please?