Nitrous filling.

I am new to refilling my own bottle and I would like to know, Can you just top off. I filled my bottle two days ago and sprayed twice. So I got a few runs left but am going out and want to be sure I'm about full. So, instead of just dumping everything in the bottle can you just top off? Will that put to much air in the bottle? I'm using the cold bottle transfer method. Thanks.

Yes you can just put it on the scale and don't over fill it. You can easily put more then 10 pounds in it but the pressure will drop off to fast. I prefer to only put 9 pounds in mine and carry a spare.