You've got several choices. Renew your visa at an immigration office and pay 100 pesos. Cross a border and then come back, paying a 50 peso fine on exit or.... do nothing. Just keep overstaying your visa.
My advice.... do nothing and let it ride unless you need a valid visa and don't renew until near that time. When you do want to renew, then make it part of a trip and cross at a border other than the Airport or Ferry (to Uruguay).
I went back and forth to renew my Visa and my opinion is that it's a waste of time and money unless you need to be legal. I'm speaking from personal experience here and not what I've heard etc... My last crossing was into Chile and I was overdue and didn't pay a fine or have a hassle.
I can explain my experiences in detail if you want but long story short is that Argentine immigration isn't that strict and they want you in the country. Crossing the most popular border spots will cost you and also draw attention.