How i get a variable value in .aspx in .aspx.cs ?

How do i get Label1 value from Repeater1 to .aspx.cs  ?
________________________________________________________
*.aspx
<asp:Repeater ID="Repeater1" runat="server"> <HeaderTemplate> </HeaderTemplate> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%#Eval("sal") %>'></asp:Label> </ItemTemplate> <FooterTemplate> </FooterTemplate> </asp:Repeater>
________________________________________________
*.aspx.cs
protected void Page_Load(object sender, EventArgs e) {
if (Label1 == "")
{do}
 }