Demand the landlord use an exterminator again. You place is habitable so you cannot just break your lease, so demand the landlord keep it up until you get the roaches gone.
Dear Tenant: You are in the City of Chicago and probably are covered by the very Tenant Friendly City of Chicago Landlord Tenant Ordinance. If that is correct, Please review the ordinance carefully on line at: http://www.chicityclerk.com/tenantsVRSlandlords.php There are specific provisions in the Ordinance which deal with Landlord issues such as the one you describe.
Follow the Ordinance and you will be able to move out without repercussions from the Landlord if the Landlord does not comply.
Hope this helps. Good luck
This is not legal advice and is not intended to create an attorney-client relationship. The post is only an opinion. You should speak to an attorney for further information. The poster is licensed only in IL. Please visit www.davismcgrath.com for more information about our services. If this post is useful to you, please remember to vote it up. Thank you.