Corn flour or corn starch works a treat. We found that if you just add a little bit & mix it together, add a little heat in microwave or pan etc that it thickens it up rather well & looks just like when you first cum & doesn't go all runny.

The other thing is if you pour some of your saved & now mixed with corn starch cum over her face or body not only does it look just the same but it kind of sticks well as well.