TKinter problem

[C D Wood]

To whom this may concern,
                                        Below is the source code, which

demonstrates a
problem I am having making a GUI for my python project  work.
'table.txt'
is a file that is read from the same folder.

My code writes to a text file 'table.txt', and 'table.txt' is displayed
in
the GUI. The user can generate new data at the click of a button
which re-writes 'table.txt', but I can only add the new table to the
GUI
 window rather than 'update' the existing one.

Any assistance would be much appreciated,

Regards,
Christian Wood.
Part III Aerospace Engineering
University of Southampton, UK.

##################################################################
from Tkinter import *

#Tkinter User Interface
class MoC:
    def __init__(self, master):
        frame = Frame(master, width=600, height=800, bd=1)
        frame.pack()

        #Button frame
	iframe4 = Frame(frame, bd=2, relief=SUNKEN)
	#Using this button below, I want to update the text box in iframe5.
        Button(iframe4, text='Display table.txt',
command=self.DisplayUpdate).pack(side=LEFT, padx=5)
        Button(iframe4, text='Quit', command=self.quit).pack(side=LEFT,
padx=5)
        iframe4.pack(expand=1, fill=X, pady=10, padx=5)

        #Text box frame
        iframe5 = Frame(frame, bd=2, relief=SUNKEN)
        text=Text(iframe5, height=10, width =70)
        fd = open('table.txt')  #table.txt must be in the same folder
        lines = fd.read()
        fd.close()
        text.insert(END, lines)
        text.pack(side=LEFT, fill=X, padx=5)
        sb = Scrollbar(iframe5, orient=VERTICAL, command=text.yview)
        sb.pack(side=RIGHT, fill=Y)
	text.configure(yscrollcommand=sb.set)
        iframe5.pack(expand=1, fill=X, pady=10, padx=5)

    #Command definitions
    def quit(self):
        root.destroy()

    def DisplayUpdate(self): #The command definition used to update the
display.
        #Could I insert a line here to remove the existing frame/text
box first?      <<<<<=====
        iframe5 = Frame(root, bd=2, relief=SUNKEN)
        text = Text(iframe5, height=10, width =70)
        fd = open('table.txt')
        lines = fd.read()
        fd.close()
        text.insert(END, lines)
        text.pack(side=LEFT, fill=X, padx=5)
        sb = Scrollbar(iframe5, orient=VERTICAL, command=text.yview)
        sb.pack(side=RIGHT, fill=Y)
	text.configure(yscrollcommand=sb.set)
        iframe5.pack(expand=1, fill=X, pady=10, padx=5)

root = Tk()
root.option_add('*font', ('arial', 10))
all = MoC(root)
root.title('2D Method of Characteristics')
root.update
root.mainloop()