Automated =SUM() Sequence?

Hi,
I have a spreadsheet with 4 sheets (while testing) that will have around 300 sheets eventually. I am adding up the value of the SAME CELL but within several other sheets (eventually all of those 300 I mentioned earlier).
I'm using =SUM for this...so far looks like this:
=SUM('001'!C15,'002'!C15,'003'!C15,'004'!C15)
as you can see the current names I've given the sheets are 001,002,003,004 - what I want to avoid is to have to manually enter " '###'!C15, " every time I create a sheet.
Any ideas? I don't think the solution must be within Excel, I just need something that creates this sequence for me, maybe another text editor..?

Actually, as I was writing this somebody just told me that what I really need is to add something to the formula so that it automatically reads from the same cell on ANY new sheet created....STILL no answer to what I need.