Legal Question in Landlord & Tenant Law in Illinois

Unless you live in a community (like Chicago, Evanston or Mount Prospect, for example) that have ordinances that have special provisions about replacement tenancies, your lease will control. But if your landlord has a replacement tenant Illinois requires parties to "mitigate" damages. So if she could replace you with a paying tenant it would be bad faith not to. If there is a gap in rent, you may be responsible for it, but again without more details that is impossible to say. At the end of the day if you move out owing rent your landlord could sue you for it if it is more than the amount of the security deposit and any damages the landlord may find on your move-out. By the way, take pictures of the apartment when you clear it out so there are no disputes as to condition, and even offer a 'walk-through' in writing. This may allay the landlord's fears, but otherwise you would need to have an attorney review the lease itself.