Increment alphanumeric string in ASP.Net using C# and VB.Net

I selected a string value from a table and i want to increase the string value by 1 i.e. i have 2 Labels Label1 and Label2.I selected into Label1 the actual string values and on Label 2.

I need to increment the string value by 1

Label1.Text = WT0008918

Label2.Text = WT0008919

My code

<asp:Label ID="Label1" runat="server"></asp:Label>
<asp:Label ID="Label2" runat="server"></asp:Label>

public partial class _1AB : System.Web.UI.Page
{
    SqlCommand cmd1 = new SqlCommand();
    SqlConnection dbConn1 = new SqlConnection();
    SqlDataReader dr;
    protected void Page_Load(object sender, EventArgs e)
    {
        string selectSQL;
        selectSQL = " SELECT Top 1 Vno FROM customer1 order by id desc ";
        dbConn1.ConnectionString = "data source=NERE\\SQLEXPRESS01; Initial Catalog=kaging;Integrated Security=True;";
        cmd1.Connection = dbConn1;
        cmd1.CommandText = selectSQL;
        cmd1.CommandType = CommandType.Text;
        try
        {
            dbConn1.Open();
            dr = cmd1.ExecuteReader();
            if (dr.Read())
            {
                Label1.Text = dr["Vno"].ToString();

                Label2.Text = "";
            }
            dr.Close();
        }
        catch (Exception err)
        {
            Response.Write(err.ToString());
        }
        finally
        {
            dbConn1.Close();
        }
    }
}

please help