Stir brown sugar, dried currants, water, vinegar, Worcestershire sauce, butter, salt, black pepper, cloves, and mace together in a saucepan over medium heat, stirring occasionally until butter melts, about 10 minutes. Bring to a boil.
Stir currant jelly into sauce and return to a gentle boil; reduce heat to low and simmer until currents are slightly plump, 5 to 10 minutes.
