As long as you have thoroughly disinfected surfaces with bleach, there should be no real risk for future cats in that particular apartment. FIP transmission is passed through either maternal transmission or forms of close contacts amoung infected cats (i.e., sharing food/water dishes, grooming, shared close contact amoung multi-cat environments, mating/breeding with an infected cat, etc).
The standard is recommending at least 6 months until introducing a healthy un-infected cat into the environment. Even the best-formed studies cannot conclude for certain how long the virus can live outside of the host/environment.
Talon has a good point about the carpets...I would at least ask your manager to ensure that all carpets and drapes are steam-cleaned before future cats are allowed into that apartment.
Just a tip, when disinfecting for infectious purposes, always allow to air-dry (or sun-dry)..this kills virals faster and more effectively than mechanical means...............Traci