I got it right, please see below for future reference:

[VBA]
Sub FillEmpty()
Dim c As Range
Dim LR As Long

Sheets("Journal").Activate
LR = Sheets("Journal").Range("C" & Rows.Count).End(xlUp).Row

For Each c In Range("B4:B" & LR)
If IsEmpty(c) Then
c.Offset(-1).Copy c
End If

Next c
End Sub

[/VBA]

You just need to call above sub in the end of your main sub.