Code:
Sub RenameCharacterStyles()
Dim oldNames As Variant
oldNames = Array("Old Style 1", "Old Style 2", "Old Style 3")
Dim newNames As Variant
newNames = Array("New Style 1", "New Style 2", "New Style 3")
Dim i As Integer
For i = 0 To UBound(oldNames)
Dim style As Style
Set style = ActiveDocument.Styles(oldNames(i))
style.RenumberList oldNames(i), newNames(i)
Next i
End Sub