Sometimes there is no other choice but total reconstruction! When the dreads have completely grown together, they are breaking and broken or completely falling out and loose. When they are not separated properly and not very solid. Or when they have become so solid during the maturing process that they have formed together and are totally matted.
There is not one technique to use in this situation. Its completely custom work tailored to the individual. Their hair type and the kind of reconstruction needed. I go through one by one and its a very time consuming process.
Please send pictures or video of your hair currently and I can advise you.