if statement will only execute once

This is code at the end of my Update() function. It calls an in game pause menu.

 if (Input.GetKeyDown(KeyCode.Escape)){
         Time.timeScale = 0;
         script = GameObject.Find("pauseObject");
         var pauseScript = script.GetComponent("pause");
         pauseScript.enabled=true;
         script = GameObject.Find("level");
         var levelScript = script.GetComponent("Level");
         levelScript.enabled=false;
    }

This is the code for resuming the game in pause.js code.

 this.enabled = false;
 function pauseMenu() {
 
     //resume game button
      if(GUI.Button(Rect(55, 150, 180, 40), "Resume Game")) {
          //Debug.Log("resume");
          this.enabled = false;
           Time.timeScale = 1;
      }
     //layout end
      GUI.EndGroup(); 
 }
  
 function OnGUI () {

     if (this.enabled){
      pauseMenu();
     }
  }

The code works perfectly the first time I pause and reenter game play. But if I try to pause again (by pushing Escape), nothing happens. Anyone have any idea why this is?