Change the position of the cans but always put the toy under the same can. Change the way you play it and encourage your child to change the game too. Games should be fun for both of you. You can use a picture or model of the objects when you play this game. After all, no one wants to see food wasted.
Appetites vary from day to day.
It's really unfair to ask your child to eat the same amount every day. Some days your child will be very hungry and will want more than you've put on his plate. Other days he will be less hungry and won't want as much. Let your child decide how much to eat. Only your child knows how hungry he is, so let him decide how much to eat.