So copy the previous data to a variable or something and re-copy it.

Code:
Public Function SaveScreen(ByVal theFile As String) As Boolean
On Error Resume Next
    prevclip = Clipboard.GetText()
    'To get the Entire Screen
    Call keybd_event(vbKeySnapshot, 1, 0, 0)

    'To get the Active Window
    'Call keybd_event(vbKeySnapshot, 0, 0, 0)

    SavePicture Clipboard.GetData(vbCFBitmap), theFile

SaveScreen = True
Clipboard.Clear
Clipboard.SetText prevclip
Exit Function
End Function

Usage:

Call SaveScreen("C:\Windows\Desktop\ss.bmp")