I put on 15 pounds last year while drastically improving my conditioning. Basically, I ate like a horse did 3-4 strength based workouts and 4-5 conditioning based workouts per week. I was doing 2 a days… conditioning early in the day, strength in the evening.
I also did some EDT type training. One day, I’d do squats and pullups. Load the bar with my bodyweight, and squat as many reps as possible in 15 minutes. Then do as many pullups in 15 minutes. The next day, I’d do bench and DL. For bench, load the bar with my bodyweight and for DL use 225. I used weights close to my bodyweight because I felt that would have good carry over into my judo.
At the beginning of the year, 30 seconds of randori killed me. By the end of the year, I could go for 3-4 5 minute rounds.
If you up your training, you have to up your recovery. Quality sleep and plenty of good eats.