how to update or refresh or reloding form

private void Item_Load(object sender, EventArgs e)
{
Autocomplete();
}

private void Autocomplete()
{
//Autocomple Name here
try
{
string query = "Select distinct txtItemCode from ItemTable order by txtItemCode asc";
SqlConnection conn = new SqlConnection(connstr);
SqlCommand cmd = new SqlCommand(query, conn);

conn.Open();
SqlDataReader dReader = cmd.ExecuteReader();
AutoCompleteStringCollection namesCollection = new AutoCompleteStringCollection();
while (dReader.Read())
{
namesCollection.Add(dReader["txtItemCode"].ToString());
}
dReader.Close();
conn.Close();
txtItemCode.AutoCompleteMode = AutoCompleteMode.Suggest;
txtItemCode.AutoCompleteSource = AutoCompleteSource.CustomSource;
txtItemCode.AutoCompleteCustomSource = namesCollection;
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}