Sub Repl()
  Dim Lr%, Lc%, Rn As Range
  Lr = Cells(Rows.Count, 1).End(xlUp).Row
  Lc = Cells(1, Columns.Count).End(xlToLeft).Column
  For Each Rn In Range(Cells(1, 1), Cells(Lr, Lc))
    If Left(Rn, 1) = """" And Right(Rn, 1) = """" Then Rn = "«" & Mid(Rn, 2, Len(Rn) - 2) & "»"
  Next
End Sub

Option Explicit

Sub ReplaceOnArray()
    Dim r As Long, c As Long
    Dim txt         As String
    Dim p           As Long

    Dim rng         As Range
    Set rng = ActiveSheet.UsedRange
    
    Dim arr         As Variant
    arr = rng.Value

    For r = 1 To UBound(arr, 1)
        
        For c = 1 To UBound(arr, 2)

            If Not IsError(arr(r, c)) Then
                txt = arr(r, c)

                If InStr(txt, """") > 0 Then
                    p = 1
                    
                    Do While InStr(p, txt, """") > 0
                        p = InStr(p, txt, """")
                        Mid$(txt, p, 1) = "«"

                        If InStr(p + 1, txt, """") > 0 Then
                            p = InStr(p + 1, txt, """")
                            Mid$(txt, p, 1) = "»"
                        Else
                            Exit Do
                        End If

                        p = p + 1
                    Loop

                    arr(r, c) = txt
                End If
            
            End If

        Next c
    
    Next r

    rng.Value = arr
End Sub

Sub tt()
    On Error Resume Next
    Set d0_ = Range("A1").SpecialCells(xlCellTypeConstants, 2)
    If Err Then Exit Sub
    On Error GoTo 0
    Application.ScreenUpdating = 0
    d0_.Replace What:="""", Replacement:="«"
    For Each d_ In d0_.Areas
        ar_ = d_.Value
        For i = 1 To UBound(ar_)
            For j = 1 To UBound(ar_, 2)
                t_ = ar_(i, j)
                n_ = Len(t_) - Len(Replace(t_, "«", ""))
                If n_ Then
                    For k = n_ To 2 Step -2
                        t_ = WorksheetFunction.Substitute(t_, "«", "»", k)
                    Next k
                    ar_(i, j) = t_
                End If
            Next j
        Next i
        d_.Value = ar_
    Next d_
    Application.ScreenUpdating = 1
End Sub

Sub Repl_()
Dim cell As Range
  With CreateObject("VBScript.RegExp")
   .Pattern = "^""(.+)""$"
     For Each cell In Range("A1:D13")
      If .test(cell) Then
        cell = "«" & .Execute(cell)(0).SubMatches(0) & "»"
      End If
     Next
   End With
End Sub

Sub Repl_Kavychki()
    Dim cll As Range, rng_1 As Range, n As Long, m As Long
    Set rng_1 = ActiveSheet.UsedRange
    arr_1 = rng_1.Value
    Set objRegExp = CreateObject("VBScript.RegExp")
    With objRegExp
        .Pattern = """(.*?)""": .Global = True
        For n = 1 To UBound(arr_1)
            For m = 1 To UBound(arr_1, 2)
                Set objMatches = .Execute(arr_1(n, m))
                With objMatches
                    For i = 0 To .Count - 1
                        arr_1(n, m) = Left(arr_1(n, m), .Item(i).FirstIndex) & "«" & .Item(i).SubMatches(0) & "»" & _
                        Mid(arr_1(n, m), .Item(i).FirstIndex + .Item(i).Length + 1)
                    Next
                End With
            Next
        Next
    End With
    rng_1.Value = arr_1
End Sub

Option Explicit

Sub ReplaceOnArrayAndKeepFormulas()
    Dim c           As Range
    Dim txt         As String
    Dim p           As Long

    Dim rng         As Range
    Set rng = ActiveSheet.UsedRange

    For Each c In rng

        If c.HasFormula Then
            txt = c.Formula
        Else

            If Not IsError(c.Value) Then
                txt = CStr(c.Value)
            Else
                GoTo NextCell
            End If

        End If

        If InStr(txt, """") > 0 Then
            p = 1

            Do While InStr(p, txt, """") > 0
                p = InStr(p, txt, """")
                Mid$(txt, p, 1) = "«"

                If InStr(p + 1, txt, """") > 0 Then
                    p = InStr(p + 1, txt, """")
                    Mid$(txt, p, 1) = "»"
                Else
                    Exit Do
                End If

                p = p + 1
            Loop

            If c.HasFormula Then
                c.Formula = txt
            Else
                c.Value = txt
            End If

        End If

NextCell:
    Next c

End Sub