Flask app not updating the page on reloading after being deployed on heroku

Question

So I have made a pretty basic flask app which shows a plotly graph template. The code pulls data from a database and updates the template, which should be reflected on the app when I reload. It works like a charm locally but when I push it on heroku, it doesn't seem to work at all. I'm not able to understand the issue here. I'll attach the code below.

app = flask.Flask(__name__)

def dir_last_updated(folder):
    return str(max(os.path.getmtime(os.path.join(root_path, f))
                   for root_path, dirs, files in os.walk(folder)
                   for f in files))

@app.route("/")
def totalNodeCount():
    plot = gp.Plot()
    plot.plotData() #Fetches data from a database and updated the testTemplate.html
    return render_template("testTemplate.html", last_updated = dir_last_updated("templates"))

if __name__=="__main__":
    app.config['TEMPLATES_AUTO_RELOAD'] = True
    app.run(host = "0.0.0.0", port = 8080)

Any help would be highly appreciated :) Thanks.