What’s the best way to tell my fwb I want to see her more often?

Recently started really enjoying sex with my fwb as we built more familiarity and trust with each other.

How can I do this while maintaining my frame? Or am I delusional and it’s not possible with a casual relationship like this?

Should I propose a schedule for meeting or is that too formal? If not a schedule, I can only hit her up more often then, which is indicating more investment on my part which may be a necessary evil in this case?