iCloud numbers reference date/value from another table
If you have a sheet for each month then simply, on the next month in question Edit the balance Bought Forward cell, start with = and then flick back to the previous table and click on the cell with the total for the month. this will then bring that balance forward - repeat the process for all the months and it will show you the projected balances for the year. I use the same type of system, have for many years and it works very well.