Update or Refresh My Variable

Dim Tweets As List(Of String) = parseTweets("hazeleekaizera")
    Private Function fetchData(ByVal Url As String) As String
        Dim callBack As String = New System.Net.WebClient().DownloadString(New Uri(Url))
        Return IIf(Not String.IsNullOrEmpty(callBack), callBack, String.Empty)
    End Function
    Function parseTweets(ByVal Username As String) As List(Of String)
        Dim tmpList As New List(Of String)
        Dim callBack As String = fetchData(String.Format("http://twitter.com/{0}", Username))

        If Not String.IsNullOrEmpty(callBack) Then
            Dim Tweets As MatchCollection = New Regex("\<p class=""js-tweet-text tweet-text""\>(.+)\<\/p\>").Matches(callBack)
            If Not Tweets Is Nothing Then
                For Each Tweet As Match In Tweets
                    tmpList.Add(Tweet.Groups(1).Value)
                Next
                Return tmpList
            End If
        Else
            Return Nothing
        End If
    End Function

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    For Each Tweet As String In Tweets
        Dim TweetText As String = New Regex("\<a href="".*?\<s\>\@\<\/s\>\<b\>(.*?)\<\/b\>\<\/a\>").Replace(Tweet, "@$1").Trim
        '// Replacing all trash tags around @mentions leaving just the mention!
        TweetText = New Regex("\<a href="".*?\<s\>#\<\/s\>\<b\>(.*?)\<\/b\>\<\/a\>").Replace(TweetText, "#$1").Trim
        '// Replacing all trash tags around #hashtags leaving just the hashtag!
        TweetText = New Regex("<a href="".*?\<\/a\>").Replace(TweetText, String.Empty).Trim
        '// Remove all remaining trash tags e.g. links/youtube/images
        TweetText = HtmlDecode(TweetText)
        TextBox1.Text += (TweetText)
    Next
End Sub

Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick
        Application.Restart()
    End Sub