agreeing with all the others, you should probably just brew a bigger beer next time. hhowever a true secondary fermentation can be done by putting sugars in the secondary. watch out for what type of sugar you use though-no table sugar, brown sugar is ok but still a little strange...i'd use invert sugar which you can find at your LHBS under that name or possibly listed as alcohol booster. this leaves no off flavors and will boost your beer however much you wwant. i'd use it in the boil of your next brew.