How to Reset Scene after Level Completion

So, when I complete a level, the game is supposed to take me back to the main menu, which it does. However, after taking me back, the game also still remembers all the objects I collected during gameplay, making levels super easy. I want to make it so that the whole scene resets after the level is completed.

 using UnityEngine;
 using UnityEngine.SceneManagement;
 
 public class GameManager : MonoBehaviour {
 
     bool gameHasEnded = false;
 
     public float restartDelay = 1f;
 
     public GameObject completeLevelUI;
 
     public void CompleteLevel()
     {
         completeLevelUI.SetActive(true);
     }
 
     public void EndGame()
     {
         if (gameHasEnded == false)
         {
             gameHasEnded = true;
             Debug.Log("GAME OVER");
             Invoke("Restart", restartDelay);
         }
     }
 
     void Restart()
     {
         SceneManager.LoadScene(SceneManager.GetActiveScene().name);
     }
 }