Most formulas estimate your caloric needs by age, height and weight. As your height and age don't change notably, the only variable is your weight.
To give you a feeling how your calories adjust with increasing weight I plotted the revised Harris-Benedict equation. I used your height (196cm) and assumed an age of 30, as you didn't mention you age. The age does not change too much, especially not for visualization purposes.
The equation only accounts for your basal metabolic rate. To reflect your exercise, I assumed moderate exercises (3–5 days per week), which adjusts the result multiplying it by 1.55.
When you weighed 200 pounds you needed approximately 3200kcal to maintain your weight. Now, as you are 220 pounds you need 3400kcal.
Continuing to eat 3500kcal would bring you (taking longer and longer) to about 230 pounds. To reach 240 pounds you would need to eat even more.
However, the math behind this makes certain assumptions (eg your body fat) and is only an approximation. Using a scale to help adjust your dietary needs is always better than simply relying on formulas.