Garnishment Question

In order to have child support garnished from your ex

My understanding is you simply have to go to the Clerk of Court - they have the Consent Order on hand - and have the Clerk issue a withholding order (based on the Consent Order) that you can then send to his employer.

My ex failed to pay his money on time and I had to have his wages garnished. In our agreement I get a 3% increase in my money each year. This is stated in our agreement that was filed with the courts. Each year in August the amount is to go up 3%. How do I get the garnishment amount changed each year? Do I have to go back to court to get it changed each year or just show the agreement to the appropriate people and get the amount changed? Since it is in our agreement, it seems silly to have to go to court each year to have it enforced.