Check your state statutes, but in SC you can file a "Memorandum of Costs" to add the interest from the date of judgment. Interest varies state to state, so you'll want to check you state's statutes on Judgments. You might call you Clerk's office (or where you filed the case) to ask what the rate is. They won't give you legal advice, but they can give you procedural information.
Hope this helps!
HBreen