You need to do Asamblea for transformation, have all shareholders sign, draft new Contrato Social (instead of Estatutos Sociales), have them all sign. Also you must publish Transformation Notice in a national paper 14 days before the Asamblea.
Costs:
Paper Ad: 1500-2000 pesos
Paperwork: 0 if you do it yourself, 10-20,000 pesos if done by lawyer.
Registro Mercantil fee: you need to pay all RM renewals if your RM is not current, then pay RM transformation fee, based upon your authorized capital. Plus you pay 100 pesos for each original filed plus 50 pesos for each copy (if you want one certified copy for yourself)***each document in the transformation package counts as ONE, including the copy of Paper Ad. My total, at the time, was 6.200 pesos for RM
If any other shareholder is transferring stock to you, he must do an "Acta de Traspaso" and this must be notarized. Notary fee RD$300 i f you do the draft, RD$1.000 or more if the notary/lawyer prepares it. Remember the old SA had 7 shareholders, the new SRL needs only 2, so you can get rid of 5 other white horses.
All in all, the transformation will run you same $$$ as registering a new company, but if you have assets/contracts in the company's name it's worth transforming. Otherwise, just get a new SRL.