Insert Blanks Rows In Alternate Rows But Ignore If Already Blank

i have this code which inserts blank rows in alternate rows,

Code:
Sub insertrow()
' insertrow Macro
Application.ScreenUpdating = True
Dim count As Integer
Dim X As Integer
For count = 1 To 20
If activecell.Value "" Then
activecell.Offset(1, 0).Select

[code].....

what changes should i make in this code to insert rows only when ther are now blank rows. So first time i run, blank rows are already there, and when i update some data at the bottom and re-run it inserts blank rows again.