Dash dance and bait out an attack to get him to whiff.
Basically, you need to find an opening one way or another. That way you can get in close to do your combos.
As for him avoiding uairs, you can try to bait his attempts at avoiding the attack, then catch him when he has no options left.
Ex: He always jump to avoid your uair out of grab or something (um...it's the only time I ever consider upairing Marth...and usually grab --> upthrow --> upair connects...). In this case, full jump, but just fast fall, so that you bait his double jump. Now that he has no jump, you can better follow his trajectory and hit him with bair or something. This is just one scenario.
Bottomline is try to bait and be more observant on how exactly he's punishing you.
Lasers help...to some degree.