Some folks call it liriope, other say big monkey grass, and some say big blue liriope. Whatever the name, and whether it is green or variegated, it needs attention now. Here is the first check before you act. Look into the center of the plant to see how tall the new growth has emerged, since you do not want to damage these new leaves. If you plan to cut yours back, which I recommend, do not cut it any lower than above the new growth. In mass locations you can use a mower with a bag set at a height just above the level of the new growth coming out. Many folks use string trimmers because they work in tight places, and that is fine. Of course, a good pair of sharp pruning shears is still my favorite way, as it allows us to observe at close range and only clip those leaves that need cutting. I can also avoid cutting the new shoots. It has been so warm that you should not delay getting to the garden task, as it will hurt the beauty of the garden all year.