Use closed values from last month as opening values for new month

Hi,

I've hit a brick wall with the following...

I would like to know if there is a way of using the last readings taken (water readings for a complex) and use them as opening readings for the new month? Other than copy and paste... There are also electricity readings but I'll add to this later. I just need to figure out the first step. I have attached an example....

Your help would be greatly appreciated