Call the police and file a report.
Call your landlord, and tell him her and her dog are still there, ask him to call the police.
Call the police the next time you see the dog on your property, and tell them that you feel the dog is a danger and you want it removed from your property immediately and permanently by whatever means necessary, refer to your prior police report as evidence.
If the dog attacks you again on your own property, kill it.
Personally, I would have shot the dog immediately the first time, you showed remarkable restraint. I have a friend who's son has permanent facial scars from a rottweiler attack as a toddler, so vicious dogs get no leeway from me.
As far as spray, it can work, but it depends on type and don't count on it working for sure, especially if the dog has a strong fighting drive or goes into a frenzy like pits do.
"Initially the dog had a good bite, but upon the first hit of spray the dog went into even a more intense fight with the suspect. Nearly half the canister was delivered before the dog was called off. The dog had received numerous shots in the eyes and nose areas during the apprehension and still the dog chose to stay in the fight. It was obvious that the dog was under a lot of discomfort. His eyes were shut tightly, but his bite never did relax."
Effects Of Pepper Spray On The Police K9 - PoliceLink