After using a command button on a gridview to activate a stored procedure, how do I 'refresh' the row in the gridview?

I am using the code below to execute a stored procedure.  The procedure results in a change in value on the displayed gridview row but the gridview doesn't show this change until I reload the page manually.  How do I make the row refresh after clicking the command button?

Protected Sub GridView1_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles GridView1.RowCommand
        If e.CommandName = "SetMessagePreference" Then
 
            Dim sConnStr As String = SqlDataSource1.ConnectionString
            Dim cnBKTest As New SqlConnection(sConnStr)
            Dim cmdTest As New SqlCommand("FGContactDetailsMessagePreference", cnBKTest)
 
            cmdTest.CommandType = Data.CommandType.StoredProcedure
            cmdTest.Parameters.Add(New SqlParameter("@ContractID", Data.SqlDbType.VarChar, 10))
            cmdTest.Parameters("@ContractID").Value = e.CommandArgument
            cmdTest.Parameters.Add(New SqlParameter("@MessagePreferenceID", Data.SqlDbType.VarChar, 10))
            cmdTest.Parameters("@MessagePreferenceID").Value = 2
 
            cnBKTest.Open()
            cmdTest.ExecuteNonQuery()
            cnBKTest.Close()
        End If
    End Sub

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