forcing excel to update last used cell?

I have some code which copies formulas from T13 down to the last used row in T13 whenever the file is saved. However I have a problem where i put something in say rows 13 to 20 but then delete rows 15-20 at some point, yet excel doesnt update the last used rows properly so when the macro in Workbook_BeforeSave runs the below code, it still thinks rows 13-20 are used and it copies the formulas down to row 20 even when 15-20 are now blank because I have deleted the ENTIRE rows (and some below that just to be sure).

I have had this problem before where excel seemingly doesnt update the last used rows until you actually exit the file and open it again so I am wondering if there is some command to force excel to update what it thinks is the last used row, so that i can get that value updated just before the macro runs the copy down formulas code, my code for reference is

Range("T13").Copy
Range("T13:T" & ActiveSheet.Cells.SpecialCells(xlCellTypeLastCell).Row).Select
Selection.PasteSpecial Paste:=xlPasteFormulas, Operation:=xlNone, SkipBlanks _ :=False, Transpose:=False

any ideas??

Hello Neowok,

You have just discovered an unsual "feature" of LastCell. It seems LastCell is loaded when the Workbook is first opened and doesn't update until it is reopened. A more reliable method is using the End Method for a range which allows you to select the last cell in a range directionally: Up, Down, Left, Right. I have made this change for you in the code line line below.

Original Code:
Range("T13").Copy
Range("T13:T" & ActiveSheet.Cells.SpecialCells(xlCellTypeLastCell) .Row).Select
Selection.PasteSpecial Paste:=xlPasteFormulas, Operation:=xlNone, SkipBlanks _ :=False, Transpose:=False


Modified Code:
Range("T13").Copy
'Get the Row Number of the last Worksheet Row
RC = Range("T:T").Rows.Count - 1

'Get the Address of the Last Cell in Column T
LC = Range("T:" & RC).End(xlUp).Address

Range("T13:" & LC).PasteSpecial Paste:=xlPasteFormulas, Operation:=xlNone, SkipBlanks _ :=False, Transpose:=False

Hope this helps,
Leith Ross

couldnt get this to work, I think its because

RC = Range("T:T").Rows.Count - 1

This may be the problem, in that column T may be completely blank except for T13 so theres no point counting the last used row based on column T, I need the last used row based on all of columns A to U,

the problem is doing this:

RC = Range("A:U").Rows.Count - 1
LC = Range("T:" & RC).End(xlUp).Address

ends up giving me a range of 65535 for RC and T13 for LC

T13 is currently the last used cell in column T, BUT I have typed some junk into O18 and its not picking this up as O being the last used row in the sheet.