Can I share what I did after doing exactly what you did above?
My crop came out better and I pulled 5 ozs with similar light and in the same tent. I assume you're growing the same or similar yielding strain as your first grow.
What I wanted next was denser, and larger nugs. I wanted the yields and so I did the math to see how I SHOULD have done IF I did it right.
It made me cry that I should have averaged 1.5-2LBS in a 4x4 tent.
THE MATH:
2 mediocre 300w lights = 30 x 2 = 60W
viparspectra 600w light = 60 x 1 = 60W
Total "real" Watts = 120W
Compared to:
1 600W HID lamp = 600W
600/120 = 5X efficiency ratio
5ozs(my yield) X 5 = 25ozs = 1.5LBS
THE LESSON:
Spend at least $500 on lights and get the most out of your plants.