如何在每一帧中加载Admob非页内广告？

Question

在我的游戏中，每个场景中都有横幅，而插页式广告则显示每隔4个GameOver。因此，我有Admob横幅和插页式广告。横幅广告效果很好，但插页式广告仅显示一次，但下次则不显示。有人可以帮助我弄清楚如何在每次需要时加载非页内广告。

我的AdManager

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using admob;

public class AdManager : MonoBehaviour
{

public static AdManager Instance{set;get;}

public string VideoId;
public string BannerId;

public void Start() {

    Instance = this;
    DontDestroyOnLoad (gameObject);

    #if UNITY_EDITOR
    #elif UNITY_IOS
    Admob.Instance().initAdmob(BannerId,VideoId);
    Admob.Instance().setTesting(true);
    Admob.Instance().loadInterstitial ();
    #endif
}

public void Update() {

    Instance = this;
    DontDestroyOnLoad (gameObject);

    #if UNITY_EDITOR
    #elif UNITY_IOS
    Admob.Instance().initAdmob(BannerId,VideoId);
    Admob.Instance().setTesting(true);
    Admob.Instance().loadInterstitial ();
    #endif
}




public void ShowBanner() {
    #if UNITY_EDITOR
    Debug.Log("[BANNER] Unable to play ads from EDITOR");
    #elif UNITY_IOS

    //Here define the size of the banner - new AdSize( width , height )
        AdSize adSize = new AdSize(350, 50);

        Admob.Instance().showBannerRelative(adSize, AdPosition.BOTTOM_CENTER, 5);
    #endif
}

public void ShowVideo() {
    Debug.LogError("[VIDEO] isInterstitialReady: " + Admob.Instance().isInterstitialReady());
    #if UNITY_EDITOR
    Debug.Log("[VIDEO] Unable to play ads from EDITOR");
    #elif UNITY_IOS
    Debug.LogError("[VIDEO] isInterstitialReady: " + Admob.Instance().isInterstitialReady());
    if (Admob.Instance().isInterstitialReady()) 
    {
        Admob.Instance().showInterstitial();


    }else{
        Debug.Log("Should not be playing video");
          Admob.Instance().loadInterstitial();
          Admob.Instance().showInterstitial();

    }

    Debug.LogError("[VIDEO] isInterstitialReady: " + Admob.Instance().isInterstitialReady());
    //Destroy(gameObject);

    #endif

}

}