How to overwrite res.send(data) when resending a POST request?

Question

JavaScript

After the first call to the POST request, data is written to res.send(), but after the second call, the data variable does not change, how to fix this?

const express = require('express');
const bodyParser = require('body-parser');
const MongoClient = require('mongodb').MongoClient;
const fs = require('fs');
const conf = {encoding: 'utf8'};
const app = express();

  app.post('/yo', urlencodedParser, (req, res) => {
    var red = {
       text: req.body.message
     }
       fs.readFile(red.text, 'utf8', (err, data) => {
          if (err) {
            throw err;
          } else {
            app.get('/yo', (req, res) => {
              res.send(data);
            });

          }
          console.log(data);

     });

     //post yo
  });