Question
do you have any idea how to prevent roots from stopping irrigations by clotting the holes?

Answer
There is really not a good way to do this.  It is a major drawback of underground drip irrigation.  Short of putting some sort of chemical in the system, the only other remedy is replacement of the tubing.  And I dont recommend using chemicals unless you are very familiar with them, and how drip irrigation systems work.  Consider using surface type lines if you replace.