How can I get the number of lives change (pygame)?

I'm new to python and pygame and so far ive managed to get everything working, but cant work out how to make my lives go down.

If you haven't worked out its a simple fruit catching game.

I've managed to make my score go up. I've tried saying if the fruit is below a certain x co ordinate take away a life but it doesn't work.

import time
import random
import pygame
from pygame import*
pygame.init()
myname=input('What is your name')
#set the window size
window= pygame.display.set_mode((800,600) ,0,24)
pygame.display.set_caption("Fruit Catch")
#game variables
myscore=0
mylives=3
mouth_x=300
fruit_x=250
fruit_y=75
fruitlist=['broccoli.gif','chicken.gif']
#prepare for screen
myfont=pygame.font.SysFont("Britannic Bold", 55)
label1=myfont.render(myname, 1, (240, 0, 0))
label3=myfont.render(str(mylives), 1, (20, 255, 0))
#grapchics
fruit=pygame.image.load('data/chicken.png')
mouth=pygame.image.load('data/v.gif')
backGr=pygame.image.load('data/kfc.jpg')
#endless loop
running=True
while running:
    if fruit_y>=460:#check if at bottom, if so prepare new fruit
       fruit_x=random.randrange(50,530,1)
       fruit_y=75
       fruit=pygame.image.load('data/'+fruitlist[random.randrange(0,2,1)])
    else:fruit_y+=5
   #check collision
    if fruit_y>=440:
            if fruit_x>=mouth_x and fruit_x<=mouth_x+300 :
                    myscore+=1
                    fruit_y=600#move it off screen
                    pygame.mixer.music.load('data/eating.wav')



    #detect key events
    for event in pygame.event.get():
            if (event.type==pygame.KEYDOWN):
                if (event.key==pygame.K_LEFT):
                        mouth_x-=55
                if (event.key==pygame.K_RIGHT):
                        mouth_x+=55

    label2=myfont.render(str(myscore), 1, (20, 255, 0))
    window.blit(backGr,(0,0))
    window.blit(mouth, (mouth_x,440))
    window.blit(fruit,(fruit_x, fruit_y))
    window.blit(label1, (174, 537))
    window.blit(label2, (700, 157))
    window.blit(label3, (700, 400))
    pygame.display.update()

When checking for the collision, use else.

#check collision
if fruit_y>=440:
         if fruit_x>=mouth_x and fruit_x<=mouth_x+300 :
             myscore+=1
             fruit_y=600#move it off screen
             pygame.mixer.music.load('data/eating.wav')
         else:
             mylives-= 1

That should work.