Is it possible to persist psycopg2 connection more than 24 hour. I tried but I could not execute successfully

Question

I have created database connection as below code. My question is basically is it possible to persist connection more than 24 hours. What my problem is current that if this code is running into application for more than 24 hours and if I don't do any insert or update on SQL from other process. Later after 24 hours even if there is new records in tables from other process. This code below return me before 24 hours value, which it executed last 24 hours back.

import pandas as pd
import psycopg2

class Database:

    def __init__(self, DATABASE_HOST, DATABASE_USERNAME, DATABASE_PASSWORD,
                 DATABASE_PORT, DATABASE_NAME):
        self.host = DATABASE_HOST
        self.username = DATABASE_USERNAME
        self.password = DATABASE_PASSWORD
        self.port = DATABASE_PORT
        self.dbname = DATABASE_NAME
        self.conn = None

    def connect(self):
        if self.conn is None:
            self.conn = psycopg2.connect(
            host=self.host,
            user=self.username,
            password=self.password,
            port=self.port,
            dbname=self.dbname)

    def rows_to_frame(self, query):
        self.connect()
        return pd.read_sql(query, self.conn)

    def fetchall(self, query):
        self.connect()
        with self.conn.cursor() as cur:
            cur.execute(query)
            records = cur.fetchall()
        cur.close()
        return records

    def fetchone(self, query):
        self.connect()
        with self.conn.cursor() as cur:
            cur.execute(query)
            records = cur.fetchone()
        cur.close()
        return records

The folder structure is as follows

Application
    --> pgconnection
        | --> __init__.py
        | --> db.py
    --> Source
        | --> main.py

For example:

__init__.py

from pgconnection import db

print(db.execute('select * from emp')

case 1: record in emp table before 24 hours -

---------------------------
id  | name   | salary      |
---------------------------
1   | Sam    | 6000        |
---------------------------
2   | Adam   | 5000        |
----------------------------

and result of above code:

print(db.rows_to_frame('select * from '))

---------------------------
id  | name   | salary      |
---------------------------
1   | Sam    | 6000        |
---------------------------
2   | Adam   | 5000        |
----------------------------

case 2:

After 24 hours new data added into emp table from other process. If I execute the query again since object is created

---------------------------
id  | name   | salary      |
---------------------------
1   | Sam    | 6000        |
---------------------------
2   | Adam   | 5000        |
---------------------------
3   | Ada    | 5600        |
---------------------------
4   | Stephen | 7899       |
---------------------------

On running main.py it is still returning result as

---------------------------
id  | name   | salary      |
---------------------------
1   | Sam    | 6000        |
---------------------------
2   | Adam   | 5000        |
----------------------------

instead of

---------------------------
id  | name   | salary      |
---------------------------
1   | Sam    | 6000        |
---------------------------
2   | Adam   | 5000        |
---------------------------
3   | Ada    | 5600        |
---------------------------
4   | Stephen | 7899       |
---------------------------

what could be the reason? I am not able to solve the issue. Please someone guide me where I am making mistake your input is valuable.