Copy Based On Column Criteria & Append To Another Sheet

I have a spreadsheet that is used to store statistical information on a monthly basis, some of this information may be incomplete and so will need to be acted upon month by month, What I need to do using VBA is: At the close of the spreadsheet check sheet1 and if there is any data (text) in cells N – Q on any line If there is move to sheet3 check for the next blank line then paste the data from only certain fields i.e. A,B, N-Q,R,S

Here is another problem

As the sheet will be used on and off during the month I don’t want data that is already been moved across to sheet3 to be copied again so there needs to be someway of checking if the info is already there? I have code now for the find last cell part of the problem.

Sub FindLastCell()
Dim LastCell As Range
With ActiveSheet
Set LastCell = .Cells(.Rows.Count, "A").End(xlUp)
If IsEmpty(LastCell) Then
'do nothing
Else
Set LastCell = LastCell.Offset(1, 0)
End If
End With
LastCell.Select
End Sub