How to refresh playerprefs?

Im making a Balloon poping game, and I want to get a prize for some amount of score for example if you made a score of 10 you get a sticker or if you made a score of 20 you get a keyholder, and if you have score 0 you get a try again text so the problem is that when I finish the game it displays the try again text then when you open a diferent program (like going to a folder o anything outside of unity the text refresh and then I get the right text. I try using update, LateUpdate and FixedUpdate but nothing changes.

here is the script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.SceneManagement;

public class CountDownTimer : MonoBehaviour
{

//public string levelToLoad;
public float timer = 60f;
public Text timerSeconds;
public GameObject panelWin, score, time, pausa;
public int _playerScore;
public Text premio;

// Use this for initialization
void Start ()
{
    timerSeconds = GetComponent<Text>();
    time.SetActive(true);
    panelWin.SetActive(false);
    Time.timeScale = 1;
}

// Update is called once per frame
void LateUpdate ()
{
    timer -= Time.deltaTime;
    timerSeconds.text = timer.ToString("f0");
    if (timer <=0)
    {
        if (PlayerPrefs.HasKey("Points"))
        {
            _playerScore = PlayerPrefs.GetInt("Points");
            if (_playerScore == 0)
            {
                premio.text = "Intenta de nuevo!";
            }
            else
            {

                if (_playerScore >= 1 && _playerScore <= 10)
                {
                    premio.text = "Tu premio es: una calco Bebé a bordo";
                }

                else
                {

                    if (_playerScore >= 11 && _playerScore <= 20)
                    {
                        premio.text = "Tu premio es: un llavero Huggies";
                    }
                    else
                    {

                        if (_playerScore >= 21 && _playerScore <= 30)
                        {
                            premio.text = "Tu premio es: un pack de toallitas";
                        }
                        else
                        {

                            if (_playerScore >= 31 && _playerScore <= 40)
                            {
                                premio.text = "Tu premio es: un pack de pañales";
                            }
                            else
                            {

                                if (_playerScore >= 41 && _playerScore >= 50)
                                {
                                    premio.text = "Tu premio es: un bolso Huggies";
                                }

                            }

                        }

                    }
                     

                }
            }
            
            
        }

        panelWin.SetActive(true);
        score.SetActive(false);
        //time.SetActive(false);
        pausa.SetActive(false);

        if (panelWin == true)
        {
            Time.timeScale = 0;

        }

        
    }

}

public void DoARestart()
{
    SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
}

public void Menu()
{
    SceneManager.LoadScene("TitleScreen");
}

}

I dont have any errors on the console, would be very glad if anyone can help!
Thanks!

You are looking for PlayerPrefs.Save().

Be afraid of using PlayerPrefs to store this kind of thing. I’ve found it to be unreliable and in the worst possible way: forces outside Unity’s control can cause the preferences to be wiped out. If it were me, I’d think about saving data to persistentDataPath. You can use a JSON formatter, a binary formatter, format the data as XML (my personal favorite), or come up with your own custom format (an excellent choice for masochists).