Spray 7-quart oval slow cooker with cooking spray. Remove excess fat from ham. Make cuts about 1/2 inch apart and 1/4 inch deep in diamond pattern around top and sides of ham. Place ham in slow cooker. In small bowl, mix preserves, brown sugar, mustard and cranberry juice until smooth. Spread or brush mixture over ham in slow cooker.
Cover; cook on Low heat setting 8 hours or until meat thermometer reads 140°F. Remove ham from slow cooker; cover with foil and let stand 10 to 15 minutes before carving.
Meanwhile, pour juices from slow cooker into 2-quart saucepan. Heat to simmering; cook until slightly thickened. Serve ham with sauce. Garnish serving platter with peach slices.