Competing on price should be left to the fast-food chains.
If your restaurant isn't achieving sufficient revenue, it's not that your prices are too high; it's the value perceived based on the price is too low.
Price your menu in a way that allows you to be profitable and create a marketable experience that justifies that price based on the value received.
A good sales and marketing process will magnify the value of the experience.
Before you invest in a sales plan, make sure the product you deliver exceeds the value you charge.