Hops recalculation

Hello
          I'm rather new in BeerSmith and though I `ve been using it in at least 10 brewing sessions I still have a doubt about hops recalculation.

        Let`s say I intend to brew a recipe in which I should get 40 l pre-boil volume and 1.050 pre- boil gravity and to get 30IBUs in three hops additions.  Now, due to inefficiencies I get my 1.050 pr- boil gravity but only 35 liters. That means that if I put my calculated hops into the boiler as they were calculated  the final beer would have let's say 38 IBUs instead of the 30 I need.

          Is there in BeerSmith any feature that lets me recalculate each new hops addition using my real pre-boil ( or post-boil Volume) ?  If not do you do it by hand? or you use any other method?

            Thanks for your advices

Happens to me most every brew session.

I use the "dilution tool" to determine how much water to add to get the gravity I want. If the volume of the batch after dilution is not what I initially calculated, I can change the efficiency and/or batch size in the recipe to get the volume and gravity of the recipe to match reality. That lets me adjust my hops to match the target bitterness. 

If you want to use the higher gravity and don't want to dilute, you can adjust batch size and efficiency to get the recipe to match reality, then adjust your hops to get the intended bitterness.

The dilution and recalculation takes a few minutes while I'm waiting for the wort to come to a boil. I usually add only half the water the dilution tool calls for then take a gravity reading, recalculate, and repeat until I get the gravity I want. This assumes you have measured and marked the volume of your brew pot accurately.

Dan