Delete duplicate gameobject on restart

Hey, I am new to Unity. I have the following code which creates a main menu :

using UnityEngine; using UnityEditor; using System.Collections; using System.Collections.Generic; using System.IO;

public class EscapeGUI : MonoBehaviour {

 public GUISkin MySkin;
 public bool pauseToggle = false;
 public bool showGUI = false;
 public bool levelLoaded = false;

 static string filePath;

 private List<string> list = new List<string>();
 private string line;

 void Update() {
     if (!levelLoaded) {
         showGUI = true;
         Time.timeScale = 0;
         Debug.Log ("NO LEVEL LOADED");
     } else {
         if (Input.GetKeyDown (KeyCode.Escape)) {
             pauseToggle = !pauseToggle;
             if (pauseToggle) {
                     Time.timeScale = 0;
                     showGUI = true;
             } else {
                     Time.timeScale = 1;
                     showGUI = false;
             }
         }

         Debug.Log("FILEPATH IS " + filePath);
         Debug.Log("LEVEL IS LOADED");
     }
 }

 void OnGUI() {
     if (showGUI) {

         GUI.skin = MySkin;
         GUILayout.BeginArea (new Rect (Screen.width / 4, Screen.height / 4, 400, Screen.width / 2));

         GUILayout.BeginHorizontal ();
         if (levelLoaded){
             if (GUILayout.Button ("Resume")) {
                 Time.timeScale = 1;
                 showGUI = false;
                 pauseToggle = false;
             }
         }
         GUILayout.EndHorizontal ();
         
         GUILayout.BeginHorizontal ();
         if (levelLoaded){
             if (GUILayout.Button ("Restart")) {
                 Application.LoadLevel (0);
                 showGUI = false;
                 pauseToggle = false;
                 Time.timeScale = 1;
                 levelLoaded = true;
                 Debug.Log ("Game is restarted with this level: " + filePath);
             }
         }
         GUILayout.EndHorizontal ();
         
         GUILayout.BeginHorizontal ();
         if (GUILayout.Button ("Load")) {
             filePath = EditorUtility.OpenFilePanel("Select JSON file",Application.streamingAssetsPath,"txt");
             Debug.Log ("Game is loaded with this level: " + filePath);

             StreamReader reader = new StreamReader(filePath);
             while ((line = reader.ReadLine()) != null)
             {
                 list.Add(line);
                 //Debug.Log(line);
             }

             //Do this as soon as the JSON is checked and found to be OK.
             GameObject.Find("Preserved Variables").SendMessage("setFilePath", filePath);

             Time.timeScale = 1;
             levelLoaded = true;
             showGUI = false;
             pauseToggle = false;
         }
         GUILayout.EndHorizontal ();
         
         GUILayout.BeginHorizontal ();
         if (GUILayout.Button ("Quit")) {
             Application.Quit();
         }
         GUILayout.EndHorizontal ();
         
         GUILayout.EndArea ();
     }
 }

}

A game is created by importing a JSON file (in the code its just txt for testing, i have not implemented the JSON part yet), in this JSON file the game flow will be described.

So basically when a player clicks load, I want the game to be playable and then when he clicks restart because of the 'Application.LoadLevel (0);' code everythings gets deleted, thus I don't know anymore what the current file (level) it was.

So I created an empty gameobject called 'Preserved Variables' and I put a C# script component in this, the script looks like this:

using UnityEngine; using System.Collections;

public class PreservedVariables : MonoBehaviour {

 public string filePath;

 public static PreservedVariables instance;

 // Use this for initialization
 void Start () {
 
 }
 
 // Update is called once per frame
 void Update () {
 
 }

 void Awake() {
     if(instance){
         Destroy(this);
     } else {
         DontDestroyOnLoad(this);
         instance = this;
     }
 }

 void setFilePath(string fp) {
     filePath = fp;
 }

 string getFilePath() {
     return filePath;
 }

}

Now the problem is that when I run this and ingame i click 'load', i select my file and so far everything is good. But then when I click "restart" I get the following 2 problems:

1) the main menu shows me only the 'load' and 'quit' as it is only supposed to show when there is no game loaded (so this only happens at startup), however i think this will be fixed by fixing nr.2 (see below)

2) As soon as i click restart after loading a file, the gameobject 'Preserved Variables' is made again but this time it does not have a script component attached. (the original gameobject has its FilePath updated correctly though).

If I may I would like to ask an extra small question to this, how do I exactly retrieve the filepath variable again from the empty gameobject 'Preserved Variables' so that I can use it in my restart code?

Sorry for the big post, I hope someone can help me!!

Thanks in advance, Dennis