Create your base surplus for non-training days. If 2,500 is maintenance, eat at 3,000. On training days just add something to compensate for lost calories from training. There's no way to know how many calories you burn training without having all sorts of medical equipment attached to you, but you can give a rough estimate just so your body has something extra to ensure you stay in a surplus.
The way I've been doing it since I started tracking my diet is training days (3-4 days a week) I'll add an additional 300 calories worth of carbs, combined with one of my usual non-training day carbs, to make a good-sized pre-workout carbup (120g carbs, to be exact). Also, as I eat beef 3-4 times a week, I'll also have the beef on my training days. I substitute one of my other meat sources from the non-training days. Every day I eat 7oz salmon, which I never replace, 6oz poultry, and another 3-4 oz of some other meat (needs to be around 120-150 calories, and 20-30g protein, preferably 25g. I might have the smaller protein source be 3oz X lean ground turkey, so I still get poultry, but then take out my 6oz salmon in place of 5oz lean ground beef, which has the 40g protein the chicken does (at about the same bioavailability), but more calories and fat, so it will bring up my daily calorie total with the carbs by about 450. So, if on non-training days my total is 3,600, on training days it becomes around 4,050. I'll add a bit more if I'm running after I workout. My runs are usually 4-6 km, which is enough to burn off several hundred calories in someone 200 lbs.