Maintain (Keep) DropDownList Selected Text after PostBack in ASP.Net Repeater

I want to maintain the state of the DropDownList selected text after PostBack but the DropDownList is nested inside a Repeater Control Header.

<asp:Repeater ID="rpControl" OnItemDataBound="rpControl_ItemDataBound" runat="server">
    <HeaderTemplate>
        <table id="tblControl" class="table table-striped table-bordered table-hover table-condensed" border="1">
            <tr>                                       
                <th style="text-align: center; vertical-align: middle; width: 150px;">Location<br />
                    <asp:DropDownList ID="cboLocation" Width="100%" runat="server"></asp:DropDownList></th>
    </ItemTemplate>
    <FooterTemplate>
        </table>
    </FooterTemplate>
</asp:Repeater>