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Expect to need to do a more thorough job of reseasoning now and then even if you give your Dutch oven a quick one after each use. How often this needs to be done will vary from person to person (for instance, if you use it to cook a lot of acidic foods, you will probably have to do so more often than someone who doesn’t). Thoroughly reseason your cast iron whenever:   Foods begin to stick to it constantly. Rust recurs frequently and/or pervasively. The cast iron turns from shiny and black to dull and gray. Definitely use a mild dish soap to wash it this time for a more extensive clean. Instead of a sponge, however, use a cleaning brush with stiff bristles for an even more rigorous job. Give it a thorough rinse with hot water and then dry it off. Wipe it down with more cooking oil. This time, however, do it all over: both inside and out. Do a thorough job, but keep the application thin. Wipe away any excess with fresh paper towels if needed. First, expect oil to possibly drip from your Dutch oven while it bakes, even if you did a good job of removing the excess. Cover the lower rack with aluminum foil to keep the bottom of your oven clean. Then set your Dutch oven upside-down on top of that. Turn the oven on. Heat it up somewhere between 350 and 400 degrees Fahrenheit (177 and 204 degrees Celsius). Once your oven reaches your desired temperature, let the Dutch oven cook inside it for a minimum of one hour. After that, it’s good to go.

Summary:
Reseason as needed. Wash with mild soap and a brush. Oil it up again. Put your cast iron in the oven. Bake your cast iron.