How to update text in PyGame?

I wanted to make a game, where player can move to any arrow and get a point for so. I can render the text, but cannot update it.

My code:

import pygame, sys
from pygame.locals import *
import random
import time

pygame.init()
 
FPS = 60
FramePerSec = pygame.time.Clock()

BLACK = (0, 0, 0)
WHITE = (255, 255, 255) 
GRAY = (200, 200, 200)

SCREEN_WIDTH = 400
SCREEN_HEIGHT = 600

running = True
display = pygame.display.set_mode((400,600))
display.fill(WHITE)
pygame.display.set_caption("Game")


class Up(pygame.sprite.Sprite):
      def __init__(self):
        super().__init__() 
        self.image = pygame.image.load("up.png")
        self.rect = self.image.get_rect()   
        self.rect.center=(40,0) 
        self._layer = self.rect.bottom 
 
      def move(self):
        self.rect.move_ip(0,10)
        if (self.rect.bottom > 600):
            self.rect.top = 0
            self.rect.center = (random.randint(30, 370), 0)
 
      def draw(self, surface):
        surface.blit(self.image, self.rect) 

class Down(pygame.sprite.Sprite):
      def __init__(self):
        super().__init__() 
        self.image = pygame.image.load("down.png")
        self.rect = self.image.get_rect()   
        self.rect.center=(40,0) 
        self._layer = self.rect.bottom 
 
      def move(self):
        self.rect.move_ip(0,10)
        if (self.rect.bottom > 600):
            self.rect.top = 0
            self.rect.center = (random.randint(30, 370), 0)
 
      def draw(self, surface):
        surface.blit(self.image, self.rect)

class Left(pygame.sprite.Sprite):
      def __init__(self):
        super().__init__() 
        self.image = pygame.image.load("left.png")
        self.rect = self.image.get_rect()   
        self.rect.center=(random.randint(40,SCREEN_WIDTH-40),0) 
        self._layer = self.rect.bottom 
 
      def move(self):
        self.rect.move_ip(0,10)
        if (self.rect.bottom > 600):
            self.rect.top = 0
            self.rect.center = (random.randint(30, 370), 0)
 
      def draw(self, surface):
        surface.blit(self.image, self.rect) 

class Right(pygame.sprite.Sprite):
      def __init__(self):
        super().__init__() 
        self.image = pygame.image.load("right.png")
        self.rect = self.image.get_rect()   
        self.rect.center=(random.randint(40,SCREEN_WIDTH-40),0)
        self._layer = self.rect.bottom 
 
      def move(self):
        self.rect.move_ip(0,10)
        if (self.rect.bottom > 600):
            self.rect.top = 0
            self.rect.center = (random.randint(30, 370), 0)
 
      def draw(self, surface):
        surface.blit(self.image, self.rect) 


E1 = Up()
E2 = Down()
E3 = Left()
E4 = Right()

global rt, score
rt, score = 2, 0,
text = f"Score: {score}"

def change(val):
    global rt
    rt = val

def getpoint():
    global score, text
    score += 1
    text = f"Score: {score}"

font = pygame.font.SysFont("Arial.ttf", 18)
img = font.render(f'Score: {score}', True, BLACK)
display.blit(img, (20, 20))

class Player(pygame.sprite.Sprite):
    def __init__(self): 
        super().__init__() 
        self.image = pygame.image.load("Player.png")
        self.rect = self.image.get_rect()
        self.rect.center = (160, 520)
    def update(self):
        pressed_keys = pygame.key.get_pressed()
        if self.rect.left > 0:
            if pressed_keys[K_LEFT]:
                self.rect.move_ip(-10, 0)
        if self.rect.right < SCREEN_WIDTH:        
            if pressed_keys[K_RIGHT]:
                self.rect.move_ip(10, 0)
        
        collide = {
            "1": "self.rect.colliderect(E1.rect)",
            "2": "self.rect.colliderect(E2.rect)",
            "3": "self.rect.colliderect(E3.rect)",
            "4": "self.rect.colliderect(E4.rect)"
        }

        if eval(collide[str(rt)]):
            change(random.randint(1, 4))
            getpoint()
 
    def draw(self, surface):
        surface.blit(self.image, self.rect)     
 
         
P1 = Player()

font = pygame.font.SysFont(None, 48)
img = font.render(text, True, BLACK)
rect = img.get_rect()
rect.topleft = (20, 20)

while running:   
    for event in pygame.event.get():              
        if event.type == QUIT:
            running = False
    
    P1.update()
    eval(f"E{rt}.move()")

    display.fill(WHITE)
    display.blit(img, rect)
    P1.draw(display)
    eval(f"E{rt}.draw(display)") 
    pygame.display.update()
    FramePerSec.tick(FPS)

pygame.quit()

---

My game assets:

down.png:

up.png:

left.png:

right.png:

Player.png:

---

Output: Score displayed does not change

I need to get the score in screen changing, the variable score changes.