well you can't do both at the same time, so whatever is done first, that
event gets fired.

The only way to repopulate a cell with any value or formula is to have that
value/formula saved somewhere so that if the target cell value is "" you can
recover the data.
One way would be to have a hidden sheet. each time a valid entry id  made,
the value is also copied to the same cell in the hidden sheet. if a cells
value is deleted, then the 'saved' value is recovered. of course the copy
sheet doesn't have to be hidden.

In this example sheet1 is ny data entry sheet and sheet3 is the copy.put the
code in sheet1's code page

Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
   If Trim(Target.Value) = "" Then
       Target = Worksheets("sheet3").Range(Target.Address)
   Else
       Worksheets("sheet3").Range(Target.Address) = Target
   End If
End Sub

enter a value into any cell on sheet1. look at sheet3 - see that value. back
in sheet1, change the value & check sheet3. in sheet1 delete the value...the
last good value appears. enter a space and the last good value appears