I don't know if you've done this already, but my first suggestion is to check and recheck the viv temps. Stop handling except for putting in the deli for feeding attempts 5 days or so apart. Tape paper around the viv to give the snake complete seclusion.
Before anything else, I'd say try a live red (day-old pink). Any time you attempt a feeding, leave the snake in it's deli in it's viv overnight with no checking at all. If the live pink isn't eaten in the morning, leave it in the deli all the next day, again without checking. (If it's still not eaten after this, freeze it, and try another live one 5 days later).
A lot of people have also had success with washing a pink in ivory soap. Weirdly enough, Lil used to need her live pinks washed before she'd eat them!
Fingers crossed for you. (The reason I'm suggesting other things before trying tuna or chicken broth is because we're not talking about a hatchling that's never eaten, but one which has stopped for some reason, but others may well disagree)