Take the plant to 12/12 lighting and screw with the lighting schedule about 4 days in a row. Bet that does it.

Ps....I wouldn't consider a plant that hermies due to extreme stress (like fucking around with the lighting constantly) something with a "hermie trait." I think any cannabis plant will hermie if you stress it enough.....nature.

BUT a plant that hermies EASILY or for no real reason would be one I wouldn't breed.