Custom Editor loosing data on play

Hi! I'm trying to make a custom editor, but when I hit play, all the data gets losts, and when y stop the game, the values resets to it's defaults values.

My variables:

public GameObject [] prefabs; public int [] maxSamples; public Vector3 bufferZone;

My editor code:

using UnityEngine;

using System.Collections;

using UnityEditor;

using System.Collections.Generic;

[CustomEditor(typeof(BetterInstantiate))]

public class BetterInstantiateEditor : Editor {

 private List<GameObject> prefabs;
 private List<int> maxSamples;

 public override void OnInspectorGUI()
 {
     BetterInstantiate betterInstantiateScript = (BetterInstantiate)target;
     betterInstantiateScript.bufferZone = EditorGUILayout.Vector3Field ("Buffer Zone:", betterInstantiateScript.bufferZone);
     if (this.prefabs == null) //Aún no hemos creado los ArrayList
     {
         this.prefabs = new List<GameObject>();
         this.maxSamples = new List<int>();
     }
     int numberOfPrefabs = this.prefabs.Count;
     EditorGUILayout.LabelField("Number of Prefabs:", numberOfPrefabs.ToString());
     if (GUILayout.Button ("Add Prefab"))
     {
         numberOfPrefabs ++;
         this.prefabs.Add ((GameObject)null);
         this.maxSamples.Add(0);
     }
     if (GUILayout.Button ("Remove Prefab") && numberOfPrefabs != 0)
     {
         numberOfPrefabs --;            
             this.prefabs.RemoveAt(this.prefabs.Count - 1);
             this.maxSamples.RemoveAt(this.maxSamples.Count - 1);
     }
     for (int i = 0; i < numberOfPrefabs; i++)
     {
         this.prefabs [i] = ((GameObject)EditorGUILayout.ObjectField ("Prefab:", (GameObject)this.prefabs [i], typeof(GameObject), false));
         this.maxSamples [i] = (EditorGUILayout.IntField("Max Sim. Objects:", (int)this.maxSamples [i]));
     }

     //Comprobamos que no haya dos prefabs con el mismo nombre
     ArrayList names = new ArrayList();
     for (int i = 0; i < numberOfPrefabs; i++)
     {
         if (this.prefabs [i] == null)
             continue;
         for (int j = 0; j < names.Count; j++)
         {
             if (string.Compare(((GameObject)this.prefabs [i]).ToString(), (string)names [j]) == 0)
                 Debug.LogError("You can't put 2 prefabs with the same name!");
         }
         names.Add(((GameObject)this.prefabs [i]).ToString());
     }

     betterInstantiateScript.prefabs = this.prefabs.ToArray();
     betterInstantiateScript.maxSamples = this.maxSamples.ToArray();
 }

}

I tried using Serializable and System.Serialize but it didn't work. The editor don't save nothing, the Vector3 is lost too, while in other custom editors I made this didn't happened.

Thank you.