With that amount of loss or gain per day it is going to be down to adjusting the length of the hairspring and not screw adjustment on the balance wheel. If the watch is losing 2 minutes per day and you are at the end of adjustment on the regulator then you will need to shorten the hairspring a touch by unpinning it and pushing it further through the stud. The only problem then is that this will put the watch out of beat. To rectify this you need to move the hairspring collet on the balance staff until you get an equal beat again. Do a little research on putting a watch in beat and you should see how its done.