Matador Regulator maintaince question!

So…my Edgun Matador .22 has been shooting kinda weird. My gun is zeroed at 50 yards. Sometimes after I run out of air and refill my gun, it groups a mildot lower or higher for a whole fill. Then, after I fill it back up, it may group a little higher or lower and there’s too much fps difference between shots. I took the Regulator out and refilled it. Do I have to shoot until the air goes low and refill to notice a difference or will I be able to tell a difference right off the get go? I haven’t had time to take it back out to test it, but I was wondering if anyone has any feedback.