How to Add Revenue & Cost Budget for existing Project

Hi Good Evening !!!

We are using R12.1.3  Project Module

We have below requirement:

Project -  KPRJ-01  is created with cost budget 10000  and revenue  budget 12000

Some percentage of  revenue budget – invoice created and transferred  AR

Now  customer need some services/equipment which is chargeable.

Let us say 2000 will be revenue budget and 1500 is cost budget

Now how to add this new value on the same project KPRJ-01

What is the best praise to handle this on project module

Thanks