Wash jars and place them in your canner pot, fill canner 2/3 full with water, bring to a boil. Turn off heat, cover, and keep jars in hot canner water until ready to use.
Place lids in water in a small sauce pan and heat to a low boil. Turn off heat and keep lids in hot water until ready to use.
Place the blueberries in a large saucepot and gently crush. Add the cup of juice and the pectin powder. Whisk to blend. Bring to a boil, stirring frequently with a wooden spoon.
Add the maple syrup and lemon juice and bring to a boil, letting it boil for 3 minutes. Stirring gently with a wooden spoon.
Remove from heat and ladle into jars (I used a wide mouth funnel), filling to 1/4" from the top. Wipe the rims clean with a paper towel, and screw on lids.
Put jars in boiling water in canning pot (to cover). Boil 10 minutes.