How to reference to the previous worksheet regardless of title?

[SeabeePlumber]

Hello. I am trying to create a weekly history by creating a new worksheet
each week. I name the new worksheet by using the current range of dates
covered. I then copy all cells from the previous worksheet into the new one.
The I update a couple numbers and I should be done. However my formula -->
=I10+'27JUN-02JUL'!I14 <-- stays the same in those cells that refer to the
previous sheet. instead of using the name of the previous sheet, can I refer
to the previous sheet another way? Thank fo helping.
Jay - USN