Is there a way to convert a yellow cake mix to a lemon cake? I have never done it, but wanted to try.

Mix the batter by the recipe adding the zest of one lemon and 1-2 teaspoons lemon extract.

while the cake layers bake, combine the juice of the lemon with 2 tablespoons sugar and bring to a boil  stirring to dissolve the sugar.  Cool.  

When the layers come out of the oven brush them with the lemon syrup.

Jeff's ideas sound good.  You could also replace any water in the recipe with lemon juice (preferably fresh, since you'll have one for zesting to add that to the recipe too, like Jeff suggested).  

Jeff's ideas sound good.  You could also replace any water in the recipe with lemon juice (preferably fresh, since you'll have one for zesting to add that to the recipe too, like Jeff suggested).  

Jeff's ideas sound good.  You could also replace any water in the recipe with lemon juice (preferably fresh, since you'll have one for zesting to add that to the recipe too, like Jeff suggested).  

Thank you Jeff_Arnett and CakesbyCaralin!!