In food processor slightly chop the 6 cups of Blueberries. Add to a large pan and add the sugar and lemon juice. Bring to a rolling boil that cannot be stirred down. Add the liquid pectin and bring back to a boil again for 1 minute. Ladle the hot berry mixture into jars. Wipe tops and place lids on jars and screw caps into place. Place in water bath canner with 1 inch of water covering jars. Bring to a full boil and cover for 10 minutes. Remove jars from water bath after 10 minutes and place on counter to cool. Listen for tops of jars to pop and seal. Cool completely. Jam should be good in jars for up to 1 year.