Now this is the way I solved it with the help given me above by Karthik:
Protected Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Dim timer_arr() As String
Dim timer As String
timer = Button1.Text
timer_arr = timer.Split(":")
Session("seconds") = Integer.Parse(timer_arr(2))
Dim minutes = Integer.Parse(timer_arr(1))
Dim hours = Integer.Parse(timer_arr(0))
If Session("seconds") = 0 And minutes = 0 And hours = 0 Then
Timer1.Enabled = False
Else
Session("seconds") = Session("seconds") - 1
End If
If (Session("seconds") < 0) Then
Session("seconds") = 59
Session("minutes") = Session("minutes") - 1
End If
If Session("minutes") < 0 Then
Session("Minutes") = 59
Session("TimerRemaining") = Session("TimerRemaining") - 1
End If
Button1.Text = Session("TimerRemaining").ToString() & ":" & Session("Minutes").ToString & ":" & Session("Seconds").ToString
If Session("TimerRemaining") = 0 And Session("minutes") = 0 And Session("seconds") = 0 Then
Button1.Enabled = False
Timer1.Enabled = False
End If
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
Session("TimerRemaining") = 1
Session("Minutes") = 0
Session("Seconds") = 0
Button1.Text = Session("TimerRemaining").ToString() & ":" & Session("Minutes").ToString & ":" & Session("Seconds").ToString
End If
End Sub
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:Button ID="Button1" runat="server" Text="Button" />
<asp:Timer ID="Timer1" runat="server" Interval="1000">
</asp:Timer>
</ContentTemplate>
</asp:UpdatePanel>
</div>