Sub Demo()
Application.ScreenUpdating = False
Dim i As Long
With ActiveDocument.Range.Find
  .ClearFormatting
  .Replacement.ClearFormatting
  .Text = ""
  .Replacement.Text = ""
  .Forward = True
  .Format = True
  .Wrap = wdFindContinue
  For i = 1 To 4
    .Style = "Heading " & i
    .Replacement.Style = "Schedule Level " & i
    .Execute Replace:=wdReplaceAll
  Next
End With
Application.ScreenUpdating = True
End Sub