If really set on growing carrots there nxt yr, you could try interplanting them with onions, chives, garlic or the like, but most advice, as Verdun's, is not to plant a crop in the same soil two yrs in a row. This is how crop-specific pests build up in the soil. Avoid growing plants of the same family in the same place again the next yr. If you are growing all the same plants again, and re-using the compost/soil, use a crop rotation system as you would for beds. re-vitalize the compost as verdun suggests, then put the plants into different pots than last yr. Remember that toms and pots sre in the same family, so don't put a tom into last yrs potato container unless you have completely changed the compost and cleaned the pot.
However, having said all of this, all of my fruit and veg growing used to be in containers as i had a concrete yard. I used to mix in some home-made compost and a little growmore each yr, then feed as neccessary and never had any probs. Containers can be more work in watering and feeding, but easier to control pests and diseases. I am finding more probs in my raised veg beds than I ever did with growing in containers.