Place the ham cut-side down inside the slow cooker. If the piece is too large to fit comfortably, either trim excess portions or divide the ham into halves.
In a separate mixing bowl, combine the brown sugar, maple syrup, fruit juice or cider, Dijon mustard, cloves (if using), and apple cider vinegar. Whisk thoroughly until the mixture forms a smooth glaze.
Gently pour the prepared glaze over the ham, allowing it to flow into crevices and between slices if using a spiral-cut ham.
Secure the lid on the slow cooker and set to cook on the LOW setting for 4 to 6 hours. Baste the ham with the cooking juices periodically to enhance flavor and moisture.
Approximately 20 minutes before the cooking time concludes, incorporate the butter into the liquid in the cooker. Stir until melted and well blended into the glaze.
If a caramelized finish is desired, transfer the ham to a broiler-safe dish, spoon some glaze on top, and broil for 3 to 5 minutes until lightly browned.
Carve the ham into slices and serve drizzled with the warm glaze. Garnish with pineapple rings and cherries for a festive presentation if preferred.