IF THEN web database

[jhts]

I am trying to figure out a way to input an if then statement in access and I am not very fluent in the coding. If you look at the attached screenshot I have the yellow and red fields. These are inputted on a form from the field, but as you can see the red fields haven't changed in multiple days. I would love to have an if then statement that will say if no value is entered then copy prior days value to the field. This would make it easier on the field worker from having to enter the same numbers over and over again. After the month the issue will switch over to the yellow fields and the same thing will happen there.

[June7]

I don't know how this could be done in web database because VBA is not available. For a normal db could do http://access.mvps.org/access/forms/frm0012.htm