First off, don't plant deeper. While tomato plants love that treatment, pot doesn't appreciate it so much. Ungrateful genus, lol!

Your friend may have been using less light, or light further from the plants. You can top if you like, or bend them over if height is an issue for you. Once you put it under natural sunlight, the strain should behave the same as last year.

Some growers report a loss of vigor after a plant has been re-generated by cloning only for several years- you might also consider buying a fresh set of beans, and doing a seed run (Northern Lights is stable and reproduceable) so that you always have that option. I personally have not noted this, but that's just me, and I've only been growing for about 3 years. Well, pot anyway. I've been trying to master the Elusive Chia Pet 'Fro for years