Solve a formula issue

I use this formula to pull day from a loan statement yet every month I have to update to the next months cell number is the any way to have it pull from the next month automatically here the formula. Sum( 'General sheet name '!$H$16:$H$259) so what I need to happen is the H259 cell need update to H260 next month now I use this in 300 plus work sheets. So all of the ate being updated manually. A easy solution would be great

Why not just use Sum( 'General sheet name '!$H$16:$H$99999)?

The range can extend far beyond the data to accommodate future entries. Are the values of H formula dependant?

If you can, attach a sample of your work so we can get a better idea how to assist you.