Any tips as to how to do this? How do you usually use time during the refractory period? Do girls usually charge more for this?

$$$ money talks
usually double

I disagree about "double", of course theoretically max you pay is double (u can leave and come in again) but they would give discount.

I typically say if a girl was charging 400 buck, 500 for double is easily doable. But this isn't the case for VERY popular girls. The day and time of the day also very important - obviously if you visit her during golden hour of 6pm she just wants u to get done with to see another customer.

But if this was rainy Saturday afternoon at 1pm where absolutely no one is punting, she's willing to just charge u small extra for 2nd shot.

Guicci at WC charges 500 for 1 shot and 800 for 2 shot if that's of any guide but that's the rich scale. I think you can say 30% is fair price for extra shot, 50% is max. 100% extra you are better off finding another girl

If you were adding a second girl and doing them both, the second girl would cost 50%. So that's your max.

The thing that works for me though...is just pull out an extra 100 RMB (or whatever that would be where you are) bill, put it on the table and say "1 more time...quickly, ok?". It's important to actually take the money out before you say what you're thinking. It's a subtle psychological trick. Her act of saying no will make the money go back to your wallet. She wants to avoid this because it seems like the money is already hers or at least half way to her. If you trust her you could have actually handed it to her before you said what it was for. Her hand would willingly grasp it thinking it's a tip. Once she discovers your intent, she might try to raise you. If she raises you, just pick the money back up (or motion to give it back if you handed it to her)...usually she'll just say "ok fine...but quickly ok". The thing is though, once you're inside, you don't really have to be quick.

What carfield is saying about time or day is true, too.