Mix together the cream cheese, sour cream, lemon juice and chives in a medium bowl until thoroughly incorporated.
Spread about 1/4 cup of the cream cheese mixture over the first crepe and place on a serving platter. Top with a single layer of cucumber strips, followed by a layer of smoked salmon. Arrange some arugula leaves on top of the salmon. Spread a second crepe with another 1/4 cup of the cream cheese mixture and place on top of the arugula. (It is easiest to spread the mixture onto the crepe before placing onto the cake). Top with another layer of cucumber, salmon and arugula. Continue layering in this pattern until you have used all but one of your crepes. Top the last crepe with the remaining cream cheese mixture and place on top. Sprinkle the dill over top to garnish.
This cake is best served immediately, but can also be kept in the fridge for up to an hour. If not serving immediately, wait until ready to serve before topping with the dill.