“Should I dump the soil that I used last year in my raised beds and replace it with new soil or can I use it for my crops again this year?”
The short answer: Reuse that soil! This will save you money, time and physical effort. However, recognize your soil will likely need some attention for your plants to thrive. You can do a soil test to determine what nutrients are needed. You should also incorporate organic matter to improve the porosity and fertility. Additional garden soil may be added to bring the height up for raised beds where compaction has occurred.
The long answer: There are several things to consider to answer this question. Initially I’m wondering what type of raised beds these are. Raised beds could be containerized structures made of wood or bricks with soil brought in from an outside source. They could also be shaped using just garden soil that is mounded higher than the rest of the landscape. These types of raised beds are more likely to suffer compaction from foot traffic than those elevated higher off the ground with a physical frame.
Once I know this I want to know, “How did the plants in the raised beds perform last year? Were there any signs of disease or pests?” Many diseases and pests can overwinter in the soil and will multiply the problem this year if not treated properly. This is one reason crop rotation is important even in raised beds. Avoid planting crops from the same plant family in the same raised beds year after year. Crop rotation helps builds soil health and reduce challenges with diseases and pests.
If there was a disease/pest infestation last year in a small, containerized raised bed and crop rotation is not an option, I would consider replacing the soil with a sterilized mix to avoid fighting the problem again this year.
Nutrients are leached out of the soil during irrigation and precipitation events. Soil compaction is also a concern after a year of gardening and potentially foot traffic. Incorporate organic matter into the existing soil in raised beds each year to improve the overall soil health.