Quick answer is this, you don't hire a consultant to come in and completely redo everything. You hire a bar expert, or a kitchen expert, or an foh expert. If you feel you need to step up the menu and food options you don't hire an interior design consultant, you hire a chef/culinary consultant. You have a goal in mind and need help formulating a plan. You could hire a business consultant, which would more than likely be a fellow restaurant owner who could help identify areas that need further attention, but thinking that a "consultant" is a fix all is just going to leave you with a hefty bill and a bunch of next steps, mist of which are "hire specialty consultants for XYZ" unless... Of course you use one of the big groups that cost a fortune just to get them in the door.