Using Fill Function with a Formula

I have a 40 page workbook. The first 39 are individual unit bids and the 40th is a bid summary. I am trying to set up the summary worksheet to autofill as I input information into the indiidual bid sheets. When I go to use the fill function to copy the formula it changes the cell number instead of the sheet number (example, starting formula is ='UB1'!B2 the second is ='UB2'!B2 etc... Fill is changing the third cell to ='UB2'!B3). Is there a way to get autofill to change the sheet number and NOT the cell number?
Thanks,