Sub FindTableText()
     
   
  Dim aTable As Table, oCell As Cell
      For Each aTable In ActiveDocument.Tables
          For Each aCell In aTable.Range.Cells
   
  ' if background shading is a specific color
   
  Selection.Shading.BackgroundPatternColor = RGB( 63, 123, 196 )
   
   'Find text in the cell and replace 

  With Selection.Find
          .Text = "%"
          .Replacement.Text = " CB1"
          .Forward = True
          .Wrap = wdFindContinue
          .Format = False
          .MatchCase = False
          .MatchWholeWord = False
          .MatchWildcards = False
          .MatchSoundsLike = False
          .MatchAllWordForms = False
      End With
      Selection.Find.Execute Replace:=wdReplaceAll
   
   Next aCell
   
      Next aTable
      End Sub

Sub Demo()
Application.ScreenUpdating = False
With ActiveDocument.Range
  With .Find
    .ClearFormatting
    .Replacement.ClearFormatting
    .Text = "%"
    .Replacement.Text = ""
    .Forward = True
    .Wrap = wdFindStop
    .Format = False
    .MatchCase = False
    .MatchWholeWord = False
    .MatchWildcards = False
    .MatchSoundsLike = False
    .MatchAllWordForms = False
    .Execute
  End With
  Do While .Find.Found
    If .Information(wdWithInTable) = True Then
      If .Cells(1).Shading.BackgroundPatternColorIndex = wdGray50 Then .Text = "CB1"
    End If
    If .End = ActiveDocument.Range.End Then Exit Sub
    .Collapse wdCollapseEnd
    .Find.Execute
  Loop
End With
Application.ScreenUpdating = True
End Sub

Sub ReplaceInTable()
Dim orng As Range
    Set orng = ActiveDocument.Range
    With orng.Find
        Do While .Execute(FindText:="%")
            If orng.Information(wdWithInTable) Then
                If orng.Cells(1).Shading.BackgroundPatternColor = RGB(63, 123, 196) Then
                    orng.Text = " CB"
                    orng.Collapse 0
                End If
            End If
        Loop
    End With
lbl_Exit:
    Exit Sub
End Sub