Checking if miniboss is destroyed to spawn enemies again

Hi all, I am expanding upon the space shooter tutorial by adding my own mini-boss. I want to start another wave of enemies through the SpawnWaves function after the miniboss is destroyed. How do I go about checking if the miniboss is destroyed and restarting the Game Controller's Coroutine so that the SpawnWaves() is reactivated?

Here is the code of my GameController:

using UnityEngine; using System.Collections;

public class GameController : MonoBehaviour {

 public GameObject[] hazards;
 public GameObject shrimpyBoss;
 public Vector3 spawnValues;
 public int hazardCount;
 public float spawnWait;
 public float startWait;
 public float waveWait;
 public float bossWait;
 public float countSpawn;
 public float afterMini;
 public GUIText scoreText;
 public GUIText restartText;
 public GUIText gameOverText;

 public bool gameOver;
 private bool restart;
 private int score;

 public void Start (){
     gameOver = false;
     restart = false;
     restartText.text = "";
     gameOverText.text = "";
     score = 0;
     UpdateScore ();
     StartCoroutine (SpawnWaves ());
 }

 void Update(){

     if (restart) {
     
         if (Input.GetKeyDown (KeyCode.R)) {
         
             Application.LoadLevel (Application.loadedLevel);
         
         }


     }
 }



 public IEnumerator SpawnWaves ()
 {
     yield return new WaitForSeconds(startWait);
     while(true){
             for(int i = 0; i< hazardCount; i++){
                 GameObject hazard = hazards [Random.Range(0, hazards.Length)];
                     Vector3 spawnPosition = new Vector3 (Random.Range(-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
                     Quaternion spawnRotation = Quaternion.identity;
                     Instantiate (hazard, spawnPosition, spawnRotation);
                     countSpawn += 1;
                     //Starting Mini-Boss Mode after 50 spawns
             if (countSpawn == 10) {
                 yield return new WaitForSeconds (bossWait); //boss starts after 5 seconds
                 spawnShrimpy ();  //spawn MiniBoss


             } else {
                 yield return new WaitForSeconds (spawnWait);
             }
                             
                 
         }
         yield return new WaitForSeconds (waveWait);
         if (gameOver) {
             restartText.text = "Press 'R' for Restart";
             restart = true;
             break;
         }
 

     }
 }

 public void AddScore (int newScoreValue){

     score += newScoreValue;
     UpdateScore ();
 }

     //Mini-Boss event 
 public void spawnShrimpy(){

     StopAllCoroutines ();
     Vector3 spawnPosition = new Vector3 (0,0,10);
     Quaternion spawnRotation = Quaternion.identity;
     Instantiate (shrimpyBoss, spawnPosition, spawnRotation);

 
 }

 void UpdateScore(){

     scoreText.text = "Score: " + score;
 }

 public void GameOver ()
 {
     
     gameOverText.text = "Game Over";
     gameOver = true;
 
 }


     
 

}