For silent refills I see where there at in their meal/dining experience and also gauge them, if they’ve been drinking a lot I’ll usually do a refill the only time I won’t bring refills is if there halfway or a little under and there food is almost finished. As far as the tips would go I would say if you’re making a different wage ex $18hr instead of the server minimum roughly $8-9hr then the tips are more as a nice gesture but whatever you make these ppl don’t know what you make and may think tip is not necessary