increasing dose of Advair

I had an asthma attack last week and I am still having some problems, cant seem to get enough air. I say my doctor yesterday and he wants to increase my advair from 250/50 to 500/50. I did not think to ask him what that would do. I was tested last year and i am now allergic to our dog and cat which we have had for the past seven years. Not quite ready to give them up. Can anyone explain what the incease might do or any other suggestions.