Asking for some clarity.. my church is big on preaching…

Asking for some clarity.. my church is big on preaching forgivenesses, and helping people out of their sin, but this verse says not to even associate with these people if they’re in the church. What if the person is in the process of breaking that habit of sin, but slips up? Should we forgive & continue to try to help if they are seeking it? Or does this apply to those who don’t confess?
Thanks