how do I make my proxies auto refresh every certain interval, i also have ProxyRefresh as a link label

Code:
    Public Sub RefreshProxies()
        Try
            Dim oldCount As Integer = Proxies.Count
            Proxies.Clear()
            If Not File.Exists(My.Settings.ProxySource) Then
                Using http As New Net.WebClient
                    Dim r As String = http.DownloadString(New Uri(My.Settings.ProxySource))
                    If Regex.IsMatch(r, "[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\:[0-9]{1,5}") Then
                        For Each m As Match In Regex.Matches(r, "[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\:[0-9]{1,5}")
                            Dim url As String = m.Groups(0).ToString
                            Proxies.Add(url)
                        Next
                        Proxies = Proxies.Distinct.ToList
                    End If
                End Using
            Else
                Proxies.Clear()
                Proxies = File.ReadAllLines(My.Settings.ProxySource).ToList
                ProxyCount.Text = Proxies.Count.ToString("N0")
            End If
        Catch ex As Exception
            Debug.Print(ex.Message)
        Finally
            ProxyCount.Text = Proxies.Count.ToString("N0")
        End Try
    End Sub