Function ReplaceEK(ByVal startIndex As Integer, ByRef Text As String, ByVal _
      replaceWith As String) As Integer
        Dim stI As Integer = Text.IndexOf("{", startIndex)
        If stI > -1 Then
            Dim eI As Integer = Text.IndexOf("}", stI + 1)
            Text = Text.Remove(stI, eI - stI + 1)
            Text = Text.Insert(stI, replaceWith)
            Return eI - (eI - stI + 1) + replaceWith.Length
        End If
        Return -1
    End Function

        Dim i As Integer = 0
        Dim text As String = "Das ist ein {test} text mit {blub}n ich hoffe das" & _
          "geht...xD {leer}{}"
        Do While i > -1
            i = ReplaceEK(i, text,"Wurde ersetzt")
        Loop
        MsgBox(text)