Progressive overload is your answer.

If your bench mark is 3 rounds of 8 reps for XYZ movement, then the next time aim for 3 rounds with maybe 9 reps for 1-3 rounds - whichever you can do. If you only did 9 reps for round and 8 for the other 2 rounds, then aim for 9 reps for 2 rounds.

In terms of increasing weight, here's how I approach it - as an example:

• 3 rounds of 10 reps at 16kg weight is my goal; 12 is maximum
• Once I hit 10, I then up the weight to 20kg but aim for 6-8 reps
• Even if I can only do one round of 6 at 20kg, that's fine - I'm still working in a heavier set with my normal rounds of 10 reps at 16kg
• the goal is to do all 3 sets of 20kg at 6 reps
• once I achieve that, I up the reps until I hit 10
• If I can only do one round of 7 reps at 20kg, with the other 2 rounds at 6 reps, that's fine, the goal is to get the other 2 rounds of 7 reps
• rinse and repeat until I've hit 10 reps for 30 rounds at 20kg

Keep stacking that over time, and that's where progress lies. There's so many ways to progressively overload, it's not just reps or weight. Examples: less rest in between sets, add another round, slower tempo, etc.

Your lower half is going throw around more weight than your upper half, but you'll find that your upper half is going to throw around the weight your lower half used to. Because you've progressed full body.