Invalidate

Public Sub InitialiseAddInsRibbon(ribbon As IRibbonUI) 
   set mRibbonUI = ribbon 
End Sub 

Public Sub RefreshAddInsRibbon 
   mRibbonUI.Invalidate 
   DoEvents 
End Sub 

InvalidateControl

'Callback for editYears getText
Sub GetYears(control As IRibbonControl, ByRef sNumberOfYears) 
    sNumberOfYears = ThisWorkbook.Sheets("User Input").Range("C23") 
    If myRibbon Is Nothing Then 
        Set myRibbon = GetRibbon(sNumberOfYears) 
        myRibbon.InvalidateControl "editYears" 
    Else 
        sNumberOfYears = ThisWorkbook.Sheets("User Input").Range("C23") 
        myRibbon.InvalidateControl "editYears"    'it fails on the Else clause  
    End If 
End Sub