Can I make ravioli dough with only all-purpose flour or do I NEED semolina flour?
Pasta can be made from many types of flour.  Often, this is predicated on style of pasta or the dish.  100% AP flour will be just fine for your ravioli. I use it often when making fresh pasta. 

Substituting the AP flour for the semolina might impact the hydration.  I would hold off on the water at first.  If the dough feels too dry, add water a tablespoon at a time.  Getting the correct hydration comes with practice when making pasta.