Problems with code for keeping running total

Hi All,
I have a spreadsheet that i have been using and refining since being treasurer for an organization. My term is up and im relinquishing control to someone who is far less capable than i with Excel.
So im trying to simplify some of the monthly tasks that need to be done when entering data into this spreadsheet.

I came across this VBA code which allows me to keep a running total of a monthly collected amount.
When i enter the amount in one cell, it adjusts the total in another.
Heres is the code:

Private Sub Worksheet_Change(ByVal Target As Excel.Range)
      With Target
         If .Address(False, False) = "B25" Then
            If IsNumeric(.Value) Then
               Application.EnableEvents = False
               Range("B26").Value = Range("B26").Value + .Value
               Application.EnableEvents = True
            End If
         End If
      End With
    End Sub

The issue im having is that i have created a new sheet for each month of the year and have created ones through 2015 to help keep it simple for the new guy. While the VBA code works well, im not sure how to carry over the total from the prior months sheet to the new months sheet and still keep this code working.
Im sure there is a way and was hoping someone could help me out with this. Im no Excel guru, so please be gentle

On another note.
The work sheets for every month of the year are 46 rows x 5 columns in size with fairly simple formulas.
The only VBA code is whats posted above. With that said, at what point should i consider creating a new workbook. This current one goes from 2008 to 2015 and thus has approximately 96 sheets.