Why not? I sometimes ask for seconds in J and they're usually fine with it. Not everybody eats and so they often have extras. I usually ask for another salad or one more dessert. I flash my big smile and ask nicely.

I even did it on my way back from Hangzhou over the weekend on KA - I was in Y - but the spicy chicken noodles were great! I was really hungry and asked for one more when the crew were nearly done with their tea/coffee round - they were very nice and got me another noodle.