"If you lose your passport"
Translation:Om du tappar passet
It does not fit better. förlorar is a good translation if you lost the passport in a game of cards, or if you want to sound melodramatic or like an official text. Otherwise not so much.
I guess we'll have to approve this translation since it's not per se wrong, maybe you are talking about losing your passport in a game of poker, you can't tell from the English sentence. I just hope people won't believe this is a good way to talk about no longer having your passport, because it is not. Other ways to say this that would also be better would be blir av med or tappar bort. (with the stress on 'av' and 'bort' respectively).