if the bubbles are only on the inserts get you self a new set of insert decals, cut out the mylar over inserts + remove the old decals and stick on your new decals and hey presto no more bubbles.
make sure you get the high quality ones that don't need mylar or clear coat over them.
I have done this once before and it worked a treat.
 if you do remove the mylar you will need new decals for the inserts. one trick i have found handy is to put on the decals after you have clear coated it and the clear coat has cured properly, (leave it a few weeks) then if the decals do bubble again you can just peel them off and put on new ones with out recoating your playfield with clear coat.
here is a link i have found which is very handy if you want to remove your mylar. they use a product called goo gone which you can't buy in austrlia but can get on ebay from america.(http://pinball.flippers.info/mylarremoval.asp)