Could be a few reasons:
Not Enough Light: Make sure it gets some bright, but not direct, sunlight. If it's not getting enough light, it will prioritise growing leaves over flowers.
Watch the Water: Keep the soil consistently moist, but not waterlogged. Let the top inch of soil dry out before watering again.
Right-Sized Pot: If the pot is too big, your plant might put more energy into growing roots than flowers. Eventually it will grow into the pot and start flowering, but if you want flowers in the short-term, consider a slightly smaller pot.
Overfeeding: Use a balanced fertilizer, but don't go overboard. Too much or too little can affect flowering.
Keep it Comfy: Peace lilies like a consistent environment. Avoid sudden temperature changes or drafts.
Give it Time: Younger plants might not flower as much. Some types take a few years to get into the groove.
Check for Pests: Bugs or diseases can stress the plant. Make sure it's pest-free.
Adjusting these things can usually get your peace lily back in the mood for flowering! It won't happen overnight though, give it time. Peace Lily care tips