(as others have said - yes.)
after your first reforge, you can unlock the slayer path ability to "bank xp".
so you can earn xp while at the high earning Level 20; and put it into the "bank" (per weapon type). a full bank effectively takes to straight to Level 6 after reforging.(I always get max bank before reforging)
To add to this, you can also complete bounties and not collect them until after reforge to get an extra boost.