You would just have to apply for another credit card with 0% Apr when your other one is coming to its end of 0% Apr. Once you get accepted for that card you just have to do a balance transfer from your old card to the new card and the interest free period will start again. I can do all of it my Barclay card app, but I can imagine you could do it over the phone. You wouldn’t have to worry about a balance transfer until a couple of months before the other one runs out xx