I have had 3 cervical cerclages, the last became infected and i lost my baby girl at 20 or so weeks. should i get another this time?

Yes for cerclage: Yes, otherwise you may not be able to carry the baby to term.

Absolutely: I have a different insight to this question compared to most ob's because my wife has an incompetent cervix. It's horrible that you lost your baby because of an infection, but i would definitely recommend another cerclage for you. If you have been diagnosed with an incompetent cervix, that will never change. Get the cerclage placed early, 13-14wks, when risk for problems is lowest.