I have tried to serve a person twice in Chicago for a suit under 10k how many times must I keep trying to serve before I can just get a judgement

You can't get a judgment until you've served the defendant HOWEVER service does not necessarily mean giving it to the person by hand.  All jurisdictions allow service in other ways (I don't know what they are under Illinois law) and, if all else fails, you can petition the court to allow you to serve in some other way, generally by publication (i.e. you serve by putting an ad in a newspaper.)  It may take some time, but eventually you will have valid service.