You could add a little. The level is fairly low. The mint won't mind. Or alternatively, not. It's up to you.

Every year, about this time, I carefully turn out my mints from the pots, put new potting soil or compost mixture in the bottoms of the pots, then carefully replace the part I turned out, working fresh potting soil in around the edges, in order to bring the soil surface up near the top of the pots. In this time of rapid growth and vigor, everything recovers very quickly. Mints that were no more than an inch or two tall last week when I repotted have already jumped to 5 to 8 inches, ready for first harvest in a few days. I have just a few I haven't gotten to yet, and I have maybe 20 large pots with mints, lemon verbena, stevia, lemon grass (which I divide to plant half in the ground), and other things I keep in pots so I can take them in during the winter. All that have a soil level more than about an inch from the lip of the pot get the same treatment each spring, and I've had these plants for many years, adding a few only when something didn't work out (stevia attacked by scale during winter) or I want to try something else.