Fiskars Tiller Cultivator for Garden and Lawn, Extendable (40"- 60") Gardening Hand Tool, Telescoping Rotary Hand Cultivator Tool for Soil or Reseeding Grass

I would hit it with a rotary cultivator garden hand tool first and see what you're working with. Breaking the soil up and any existing mulch that may be hardened keeping water out. Basically the old mulch can form an impermeable surface which the rotary cultivator breaks apart. Another name, also made popular on As Seen On TV, was called the garden weasel. A garden hand tool with rotating spurs that chew up soil and old mulch. Once the soil and old mulch is lose, you can add more mulch if you choose to. Just adding more mulch on top of impermeable older mulch would not be recommended. Fiskars Cultivator