You have probably been charged with a probation violation. It will be necessary to arraign the case, appear before the court and convince the Judge to reinstate the probation and permit you to pay the balance. There may be new penalties added for the probation violation.
As you are aware, you may be arrested at any time. I would advise you speak to an attorney who handles criminal and traffic matters as soon as possible.
When you were convicted, you were required to comply with the terms and conditions imposed by the court. When you missed payments, the court was notified and, a bench warrant was issued for your arrest.
You should contact an attorney to assist you in having the case added to calendar. Depending on the jurisdiction, the court, at that time, can recall the bench warrant with your appearance. If you have the funds available to pay the balance of the fine on that day, it will certainly assist your situation.
To be honest, the best and easiest way to handle it would be to hire a lawyer to go into court for you and recall the warrant and have you reinstated in probation. This is generally a routine problem to have which results from not paying a fine or doing a class you were supposed to do. Handling it yourself would require you actually going into court. It is very possible that you will be able to accomplish the same thing on your own, but you can probably have a lawyer do it for relatively inexpensive and then you wouldn't have to worry at all!