DontDestroyParentのサンプル。SingletonMonobehaviourを利用

GUIController.cs

using UnityEngine;
using System.Collections;

//  シーン１のGUI
public class GUIController : SingletonMonoBehaviour<GUIController> {

	void OnGUI()
	{
		GUILayout.BeginHorizontal();
		if(GUILayout.Button( "add score: " + ScoreController.Instance.score, GUILayout.Height(50) ))
		{
			ScoreController.Instance.score ++ ;
		}
		GUILayout.EndHorizontal();

		if( GUILayout.Button("go next scene") )
		{
			// スコアコントローラーは一時保存
			this.DontDestroyOnNextLoad(ScoreController.Instance);
			Application.LoadLevel(1);
		}
	}
}

ResultGUIController.cs

using UnityEngine;
using System.Collections;

// シーン２のGUI
public class ResultGUIController : SingletonMonoBehaviour<ResultGUIController> {

	public GUIText guiText = null;

	void Start()
	{
		guiText.text = ScoreController.Instance.score.ToString();
	}

	void OnGUI()
	{
		if( GUILayout.Button("go back scene") )
		{
			Application.LoadLevel(0);
		}
	}
}

ScoreController.cs

using UnityEngine;
using System.Collections;

// スコア
public class ScoreController : SingletonMonoBehaviour<ScoreController> 
{
	public int score = 0;
}