How to refresh the flask web page?

Recently, I have a project is to implement the dynamic plotting on a web page.

Here is my python code

from flask import Flask
#from flask import render_template
import matplotlib.pyplot as plt
import io
import base64

app = Flask(__name__)

@app.route('/plot')
def build_plot():

    img = io.BytesIO()

    y = [1,2,3,4,5]
    x = [0,2,1,3,4]
    plt.plot(x,y)
    plt.savefig(img, format='png')
    img.seek(0)

    plot_url = base64.b64encode(img.getvalue()).decode()

    return '<img src="data:image/png;base64,{}">'.format(plot_url)
if __name__ == '__main__':
    app.run(debug=True, host='0.0.0.0')

Here is my HTML code

<!DOCTYPE html>
<html>
    <head>
        <title> Plot</title>
        <meta content='5; url=http://127.0.0.1:5000/plot' http-equiv='refresh'>
    </head>
    <body>
        <img src="data:image/png;base64, {{ plot_url }}">
    </body>
</html>

Although I add <meta content='5; url=http://127.0.0.1:5000/plot' http-equiv='refresh'> into my HTML code, it still can not refresh automatically.

If I want to observe the change of the plotting, I still need to refresh it manually.

Can anyone help me to solve this problem? Thanks a lot