Refresh panel with prefab contained value from json that created using array

Hello, therefore this is project for thesis at my Uni. So your help means a lot for me, I might give you a shout out on my thesis.

I made a panel displaying prefab(s) based on data that has given by json. So if json have 3 array in it, it will generate 3 prefabs contained the data from json. My main problem is, I made a button inside the panel, that button supposedly a reset button that can delete all of the data on database(which is works fine) but i have an issue on reloading prefabs based on the data itself(which is null,cause the code to delete the data on DB works fine). Here is my code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 using System.Linq;
 
 public class getOrder : MonoBehaviour {
     public string json;
     public Text display;
     public GameObject orderListPrefab;
     public GameObject canvasPanel2;
     public GameObject parentPanel;
     public Button ExitPanel2;
     public Button resetBtn;
     public GameObject sushiRaycast;
     public GameObject utama;
     Dictionary<string, string[]> hasil;
 
     IEnumerator Start()
     {
         string uname = PlayerPrefs.GetString ("namaUser"); 
         WWW w = new WWW ("http://192.168.0.14:8080/sushiresto/getUserOrder.php?nama="+ uname);
         yield return w;
         json = w.text;
         getList();
         ExitPanel2.onClick.AddListener(() => closePanel());
         resetBtn.onClick.AddListener (() => resetOrder ());
     }
 
     [System.Serializable]
     public struct UserOrderList
     {
         public string pesanan;
         public string jumlah;
         public string harga;
     }
 
     [System.Serializable]
     public class orderData{
         public List<UserOrderList> orderList;
 
     }
 
     public void getList () {
         orderData data = JsonUtility.FromJson<orderData>(json);
 
         while (this.transform.childCount > 0) {
             Transform c = this.transform.GetChild(0);
             c.SetParent (null);
             Destroy (c.gameObject);
         }
 
         //here is the code that generate prefab dummy on each array on json's have
         foreach (UserOrderList getData in data.orderList) {
                 GameObject listPrefab = (GameObject)Instantiate (orderListPrefab);
                 listPrefab.transform.SetParent (parentPanel.transform, false);
                 listPrefab.transform.SetParent (this.transform);
                 listPrefab.transform.Find ("Nama Sushi").GetComponent<Text> ().text = getData.pesanan;
                 listPrefab.transform.Find ("Harga").GetComponent<Text> ().text = getData.harga;
                 listPrefab.transform.Find ("Jumlah").GetComponent<Text> ().text = getData.jumlah;
                 print (getData.pesanan + " " + getData.jumlah + " " + getData.harga);
         }
     }
 
     void resetOrder(){
         string username = PlayerPrefs.GetString ("namaUser"); 
         string CreateUserURL = "http://192.168.0.14:8080/sushiresto/deleteorder.php?usernamePost=" + username;
         WWWForm form = new WWWForm ();
         form.AddField ("usernamePost", username);
         WWW www = new WWW (CreateUserURL, form);
 
         Debug.Log ("Triggered Tes");
     }
 
     void closePanel(){
         canvasPanel2.gameObject.SetActive(false);
         sushiRaycast.gameObject.SetActive(true);
         Debug.Log ("Triggered Close");
     }
   
 }

This is the panel and the main prefab inside of it.

This is the panel looks like on play mode