Change coolant from the green to the extended...

I have been told that it has lasted the three years and should be flushed if I change it, or just drain and put same type back into RV. Same stuff requires the monitoring of SILICA I believe its called and I would rather go with what I perceive as being better. If I get most of it out draining and the filling with water and then draining again, won't it be ok to then put the new type coolant in?