I am making a program to keep track of my barbell lifts. everything is working fine except I want the user.appendLifts() function to update the value of whichever key is being updated in liftsDict. I go through the process by starting the program, then i hit 1 to update lift, then 1 again to update my bench, and when i enter my new bench it takes me back to the previous loop but doesnt update the json file

import json
# data storage
from os.path import exists as file_exists
# checks if files exists


class Trainee():
    def __init__(self):
        # Dictionary of trainee lifts. Lists used to track progress 
        self.liftsDict = {
        'Benchpress weight': [],
        'Press weight': [],
        'Squat weight': [],
        'Deadlift weight': []
        }

    def appendLift(self, lift, weight):
        # Update lifts stored in json file
        with open('user.json', 'r') as f:
            data = json.load(f)
            liftsDictJson = data['liftsDict']
            
            lift = lift.title()
            try:
                weight = int(weight)
            except ValueError:
                print(f'{weight} is not a number')
            
            if lift in liftsDictJson:
                liftsDictJson[lift].append(weight)
                print(f'n{lift} set to {weight}')
        
                with open('user.json', 'w') as f:
                    json.dump(data, f, indent=4)

    
    def toJSON(self):
        # Save instance data to JSON file
        with open('user.json', 'w') as f:
            json.dump(self.__dict__, f, indent=4)


# Initialize program
user = Trainee()
user.setup()

while True:
    message = """Welcome back!
    Make a selection by entering a number:
    [1]Update working sets
    [2]Exit
    : """
    reply = input(message)
    if reply == '1':
        message = """Which lifts would you like to update?
    [1]Benchpress 3x5
    [2]Press 3x5
    [3]Squat 3x5
    [4]Deadlift 1x5
    [5]Back
    : """
        if reply == '1':
            message = input('Enter new working set for benchpress 3x5: ')
            user.appendLift('Benchpress', message)
    if reply == '2':
        break

I am not sure where to even begin, ive watched videos and scowered the web, asked chatGPT but nothing is really coming close