Thanks Intruder. Unfortunately we don't have the B5F on the -400 at my present employer.
I agree that that the second press of TOGA upon encountering windshear after a go-around has already been initiated seems prudent.
Additionally, perhaps it builds habit patterns to always press TOGA upon activation of a windshear warning. Such habits could be beneficial in the case of a windshear on departure, during which pressing TOGA might not be as instinctive for some pilots as it is during a windshear on approach/landing.
The only negative might be excessive rates of climb after the aircraft is clear of the windshear, but ideally pilots should be able to handle that easily by changing their vertical mode from TOGA to something more appropriate.