Are there any new treatments for arm laceration?

Suturing. Most deep lacerations will need suturing for proper healing.
Well . . . A cut on the arm may be deep of superficial, and if deep can require nerve, vessel, tendon, and/or muscle repair. Superficial cuts may require stitches, staples, tapes, glue, or a combination of these. There is not yet a magic laser, spray, or machine that can reattach separated edges of a cut without using some sort of mechanical approximator.