Hydrangea in Raised Beds

[Jemma]

Hi,

I'm thinking about planting out my hydrangea into a raised bed. However, I'm a little worried about the soil level lowering over time.

Would you recommend:
1. Adding more soil on top each year
2. Or, taking out the hydrangea, adding more soil to the bed and re planting
3. Something else

I'm new to gardening and would appreciate any feedback.

Thank you!