Sub Main
    Dim part As PartDocument = ThisDoc.Document

    Dim fileName As String = "C:\Temp\TextLines.txt"
    Dim textLines As String() = System.IO.File.ReadAllLines(fileName)
    For Each textLine In textLines
        UpdateSketchText(part, textLine)
        SavePartCopy(part, textLine)
    Next
End Sub

Sub UpdateSketchText(part As PartDocument, textLine As String)
    Dim oSketch As PlanarSketch = part.ComponentDefinition.Sketches("TextStitku")
    Dim oTextBox As TextBox = oSketch.TextBoxes(1)
    oTextBox.Text = textLine
    part.Update2(True)
End Sub

Sub SavePartCopy(part As PartDocument, textLine As String)
    Dim fullFileName As String = part.FullFileName

    Dim directory As String = System.IO.Path.GetDirectoryName(fullFileName)
    Dim partFileName As String = System.IO.Path.GetFileNameWithoutExtension(fullFileName)
    Dim partExtension As String = System.IO.Path.GetExtension(fullFileName)

    Dim textWithoutWhitespaces = textLine.Replace(" ", "_")
    Dim newPartFileName = String.Format("{0}\{1}_{2}{3}", directory, partFileName, textWithoutWhitespaces, partExtension)
    part.SaveAs(newPartFileName, True)
    
End Sub