You can create a "key", to unlock and reuse your zip ties easily. It could be used to make kid locks, locking and unlocking your stuff or just to reuse your zips. All you need is just a piece of plastic or metal sheet ~1mm thick. Let's make it!
Step 1: Cutting
I made my key from 1mm aluminum sheet but you can be creative. A spare credit card or other piece of plastic could also be used for our key, just make sure it's not too thick (depends on your zip size) or too thin (cause it'll break). Take a key from your keychain, press it on your sheet and an mark a null key with a unique tip like in the photo. The shape of the tip depends on the zips you want to unlock, so take a moment and measure how big is your zip's hole. As soon as you cut your key, sharp the tip's edges or else your zip won't unlock.
Step 2: Testing
Ok, we have a key, let's test it out. You have to take a moment and think how the zip unlocks. By pushing your key into the zip, like in the video, you lift the little plastic that holds it from opening. So, first you push to lift it, and then you push to open the zip. That's all folks. Happy locking/unlocking stuff!