In a Dutch oven, combine apricots and lemon juice. In a small bowl, combine 1/4 cup sugar and pectin; stir into apricot mixture. If desired, add butter. Bring to a full rolling boil over medium-high heat, stirring constantly. Gradually stir in remaining sugar. Return to a full rolling boil, stirring constantly, for 1 minute., Remove from heat; stir in amaretto. Cool jam in Dutch oven for 5 minutes, stirring occasionally. Ladle hot mixture into eight hot sterilized half-pint jars, leaving 1/4-in. headspace. Wipe rims. Center lids on jars; screw on bands until fingertip tight. , Place jars into canner with simmering water, ensuring that they are completely covered with water. Bring to a boil; process for 10 minutes. Remove jars and cool.