I suggest you buy a new protective film. It won't cost you too much.
It's difficult to remove the dust, I suppose. You can use a bank card to get rid of the bubbles.
Protective film can be used only once. Once torn off, it won't be exactly what it was like. And you have to buy a new one.
If you really don't want to get a new film, there is a way that is very effective,and I suggest you try it. You can use the stationery tape or packing tape to stick gently the dust attached to the protective film as much as you can. This is the use the principle of surface adhesion because generally speaking, the stationery tape and packing tape are much more adhesive than mobile phone protective film, so the dust can be removed with them. But you should pay attention not to rub the tape, but to stick the dust with vertical movements. And of course, you should also make the same movements to get off the dust which is attached to the screen, and then recoat the screen with the protective film. In addition, you can also dampen the screen a little bit and then cover it with a protective film. Then you can use a bank card to squeeze out the water between the film and screen. Of course, you'd better use something to suck the water out while squeezing. Don not let the water that you squeezed out get into the phone.
