Okay. First thing, I had a really hard time trying to understand how your data is organized, try to be more clear (say how each entry in your database looks like, and not how a specific view in Tableau looks like).
But I think I got it. I guess you have a collection of entries, and each entry has a number of measure fields (profits and etc.) and an Act/Plan field, to identify whether that entry is an actual value or a planned value. Is that correct?
Well, if that's the case, I'm sorry to say you have to calculate a variance field for each dimension. Think about it, how your original dataset is structured. Do you think you can add a single field "Variance" to represent the variance of each measure? Well, you can, store the values in a string, and then collect it back using some string functions, but it's not very practical. The problem is that each entry have many measures, if it had only 1 measure, than 1 single variance field would suffice.
So, if you can re-organize your data, what would be an easier to work set (but with many more entries) is something with the fields: Measure, Value, Actual/Plan. The measure field would have a string to identify what you're measuring in that entry. Value would be a number to represent the actual measure. And the Actual/Plan is the same. For instance:
Measure Value Actual/Plan Profit 100 Actual
So, each line in your current model would become n entries, where n is the number of measures you have right now. So a larger dataset in a way, but easier to work with. Think about, now you can have a calculated field, and use some table calculations to calculate the variance only for that measure and/or Actual/Plan. Just use WINDOW_VAR, and put Measure and/or Actual/Plan in the partition.
Table calculations are awesome, take a look at this to understand it better. http://onlinehelp.tableausoftware.com/current/pro/online/en-us/help.htm#calculations_tablecalculations_understanding_addressing.html