Sub test()
    Dim rng As Range, r As Range, x, i As Long
    On Error Resume Next
    Set rng = Cells.SpecialCells(2)
    On Error GoTo 0
    If rng Is Nothing Then Exit Sub
    With CreateObject("vbscript.regexp")
        .IgnoreCase = True
        .Pattern = "(.*)(x)(.*)(\2)(.*)"
        For Each r In rng
            x = Split(LCase$(r.Value), "/")
            For i = 0 To UBound(x)
                Do While  .test(x(i))
                    x(i) = .Replace(x(i), "$1x$3.$5")
                Loop
            Next
            r.Value = Join$(x, "/")
        Next
    End With
    Set rng = Nothing
End Sub

Sub Demo()
Application.ScreenUpdating = False
Dim Rng As Range
With ActiveDocument.Range
  With .Find
    .ClearFormatting
    .Replacement.ClearFormatting
    .Text = "([0-9])[Xx]"
    .Replacement.Text = ""
    .Forward = True
    .Wrap = wdFindStop
    .Format = False
    .MatchWildcards = True
    .Execute
  End With
  Do While .Find.Found
    Set Rng = .Duplicate
    .Duplicate.Characters.Last = "x"
    With Rng
      .Start = .Duplicate.End + 1
      Do
        If Not .Characters.Last Like "[/" & vbCr & "]" Then
          .End = .End + 1
        Else
          Exit Do
        End If
      Loop
      If InStr(1, .Text, "x", vbTextCompare) > 0 Then .Text = Replace(.Text, "x", ".", 1, , vbTextCompare)
    End With
    .Start = Rng.End
    .Find.Execute
  Loop
End With
Application.ScreenUpdating = True
End Sub