If you miss your deadlift at your knees or around mid-shin height, it's common to hammer away at RDL's, good mornings, and other variations to train your posterior chain. This can be beneficial, but without a strong upper back those supplemental lifts won't do a thing.
That's why chest-supported rows should be a staple in your program when training for a deadlift PR:
Chest-Supported Row
Likewise, strong lats, traps, and rhomboids are undervalued when training your deadlift. Increasing their strength will ensure that you can keep better mid and upper back position during your pull, especially when the bar hits mid-shin height.
In Part One of my "no curls" arm specialization training series, I talked about the absurdity of most arm specialization routines. I proposed that most trainees do more than enough biceps curls and triceps press downs and don't really need more of either of them.