Rick is right on...if they need replaced have them relined, it's almost always much cheaper. However, several years ago I took the shoes out of my Mitsubishi with the intention/thought that it was time to have them relined, only to find there was plenty of shoe material left, they were just heavily glazed. A good drum and shoe cleaning with a wire wheel ( wear a mask!) and they worked like new again. Not saying your issue is simply glazing but if you get it apart and find the shoes have plenty of lining left but you've been suffering poor/ non existant brake performance they are probably simply glazed.
As far as Square1's question about readjusting them- I say absolutely, as long as they aren't so worn that rivets etc, are contacting the drum, adjust them. Just be sure you leave the proper pedal free play.