I haven't found any method yet that will cause a trunk to grow a new top without cutting off the existing top(s) first. I have tried piercing the trunk, and snipping a chunk out. Is that what you're talking about? I'm curious also.

i don't know if it'll work on dracaena, but it works on trees. it's worth trying.
notch the trunk 1-2" above where you want new bud to form: like for air-layering. cut at 45 degree angle about one third thru. push a very thin piece of plastic in the wound to prevent it from healing and wait. if your trunk is bending a lot, make sure to cut on the 'outside' of the bend, not inside (the lean can cause the wound to open and snap the trunk). do not cover.
if the bud does not form after 1 month - you can take the plastic out - i think the wound will heal. or might bud later on.

or you can try to air-layer the same cut:
take the plastic out of wound, insert a toothpick to keep it open.
take a small 7oz plastic drinking cup, cut vertically and all the way to center bottom, making a small hole in the center bottom.
push onto the trunk below wound, trunk in the hole. fill with damp sphagnum,
cut a small circle from styrofoam or other stiff plastic: cut to center, then make small hole. stuff the lid snugly in the cup, with trunk in the hole. or just wrap with plastic wrap. check from time to time and keep slightly damp. roots should form in a month. may be more. the bud might also form below the cut.
then you cut the rooted top off and plant. the cane might produce sev buds at once too. even if it's just a single cane without any leaves.

Thanks, S