you can travel to canada and get your I-20 stamped as well. and get new i-94 card. out of my numerous visit to canada. they have only taken and issued new i-94 to me when i was changing my class of visa. they neither issue new i-94 or took old one when i was traveling in the same same visa class. i think it is fair to say that you would not have any problem as long as you have maintained your status. you should have your next sem. registration, transcripts. and travel authorization from your international advisor.