In response to the title of your thread, how would you fill your carto with the drip tip still in place?

You can't just drop
juice into the drip tip to fill a carto. You don't want any
e-liquid to get into the center air hole, only where the filler material is. This is assuming you are using a cartomizer, and not a drip atomizer.
When I fill my cartos, I place a part of wooden tooth pick into the air hole to keep juice out. This eliminates me from having to blow the carto out when I'm finished filling. I then use the "drip and flip" technique. Saturate the filler with juice, then flip the carto like a thermometer. This acts like a centrifuge, forcing the juice to the bottom of the carto where the heating coil is. After several flips, I add more juice, and flip it again. I continue these two step until the carto will take no more juice, and looks like a wet slushy drink.
Remove the tooth pick, and replace the drip tip. Ready to vape.