if you're already taking a cheat day and your weight is still stable, then that is where your metabolism is set. adding 100 kcals a day to what you are already doing (including the cheat day) would be unlikely to cause a weight gain, in my opinion. if your maintenance is around 1830 kcals/day, then that is 12,810 kcals for the week. if you are currently taking in 3000kcals on sunday plus 1340 on the other 6 days, then right now you are taking in 11,040 kcals per week. so you are still at an 1800 kcal deficit for the week. if you up your intake by 100 kcals/day, that is still only 700 additional kcals for the week, taking you up to 11,740. try staying there for 2 weeks and see if your weight holds. if it does, then up your intake another 100 kcals a day, which will put you near maintenance.
this isn't the only way to do this. i'm just trying to illustrate one approach. as long as you incrementally increase back toward your maintenance kcals, your metabolism should chase your intake. keep in mind though, that if you've lost a fair amount of weight, your NEW maintenance level will be lower than before. what did you weigh when you started your cut?