Sub Macro1()
Dim oRng As Range
    On Error GoTo lbl_Exit
    Set oRng = ActiveDocument.Range
    With oRng.Find
        .Wrap = wdFindStop
        Do While .Execute(FindText:="^13")
            If Not oRng.ParagraphFormat.Alignment = wdAlignParagraphCenter Then
                oRng.ParagraphFormat.Alignment = wdAlignParagraphJustify
            End If
        Loop
    End With
lbl_Exit:
    Exit Sub
err_Handler:
    Err.Clear
    GoTo lbl_Exit
End Sub