disclaimer-I don't have any plants going at the moment and haven't since I was a kid, I've done months of research leading up to starting a grow, and have a few friends who have each been growing for about a year, and that's where my advice is coming from, not personal experience.
but everything I've read is pretty much telling me you should hang a 4 inch or 6 inch inline duct fan near the top of your tent with a lil' ducting running from it through an exhaust port near the top. Imagine about 100$ for the fan, about 15$ for the ducting, maybe 10$ for a reliable way to hang it. Assuming the room the tent is in is cooler than the air in the tent