In a pot, cover the beans with 2 inches of water and bring to a boil. Simmer over low heat until tender, about 2 hours; add water to keep the beans covered. Drain the beans and reserve the cooking liquid.
Meanwhile, in another pot, heat 2 tablespoons of the oil. Add the pancetta and cook over moderate heat until crisp, 4 minutes. Add the shallots, celery, onion, carrot and fennel, and cook until softened. Add the garlic, crushed pepper and bay leaves and cook, stirring, until fragrant. Add the tomato paste and cook, stirring, for 2 minutes. Stir in the tomatoes and broth; bring to a boil. Simmer over low heat for 1 hour. Add the beans and enough cooking liquid to thin out the soup. Discard the bay leaves; season with salt and pepper.
In a bowl, toss the arugula and parsley with the lemon juice and remaining 1 tablespoon of oil. Season with salt and pepper. Serve the soup in bowls; top with the salad.