Sexually mature males will fast for quite a while during the breeding season. If your snake is a mature male (can be small in size and still sexually mature) and is fasting due to that, then you can offer food 100 times a week and nothing will happen. Or, you can try once a week or once every two weeks until he eats again. The latter seems to make more sense.
Also, rosies have long shed cycles. They may refuse food for a week before they even dull up where it is obvious they are entering a shed cycle. Again, offering food during this time will not persuade the snake to eat.