Here are some tips to help you increase challenge and variety in your job:
Meet with your manager and ask for new challenges and skill development opportunities. Ask for a career counselling and brainstorming session to come up with ideas for moving forward.
Try a rotation program, to learn about the tasks of your co-workers and hopefully alternate your day to day responsibilities with them to improve the variety of your work. They will probably enjoy the opportunity to learn new skills themselves.
Make a list of your job variety in different areas: skills, activities, people interactions, etc. Try to focus on a different area each day.