It's really easy to provide a hook into hitting a URL from a Google Spreadsheet. Here's how we do it. Stupid simple Flask app hangs out on Heroku and listens for the URL hit, which prompts the script to do the deed.

app.py

import os

from flask import Flask
from prepare_data import prepare_data


app = Flask(__name__)


@app.route('/')
def hello():
    return 'Not giving you nothin\''


@app.route('/update')
def update():
    prepare_data()
    return 'Away we go!'


if __name__ == '__main__':
    app.run(host='0.0.0.0', port=int(os.environ.get('PORT', 5000)))

tap_url_gs.js

function onOpen() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var menuEntries = [{name: 'Submit', functionName: 'update'}];
  ss.addMenu('Update', menuEntries);
}

function update() {
  var response = UrlFetchApp.fetch('<url-to-be-visited>');

  if (response.getResponseCode() === 200) {
    SpreadsheetApp.getUi().alert('The update was a SUCCESS!');
  } else {
    SpreadsheetApp.getUi().alert('It appears something went wrong.');
  }
}