If Julien was going to tweak the lines I'd just switch Jagr and Marchand and see if that helps both lines .
Jagr - Bergeron - Seguin
- Jagr needs other offense capable linemates and this might be a perfect fit for all 3 players.
Marchand - Kelly - Peverley
- Marchand is a mucker who can also put the puck in the net, a perfect fit for Kelly and Peverley.
Leave the other two lines alone and see what happens with the offense.