How best to guide your users when you move a critical feature?

The users of my site start a single user journey via an entry point on the home page. We have trained them to do this, but since it is not the universal pattern and has monetary implications, we want to move away from it.

I am worried that by removing the current entry point that users will think that this service is no longer available and drop-off. Some education is needed and was hoping that someone can provide some research or data on what works best.

I feel that global messages and modals can be closed so easily and that people would have message blindness.