[mothered]

If you do Apple products, I found it's often easier to simply carefully cut open the film on three sides, empty/replace the contents, then glue or tape back the film. This way you don't have to replace the seal tab or ensure the seams are perfectly symmetrical. If done properly it's invisible to the untrained eyes.

I've actually written a guide to this effect.

You're not working to meet a deadline, so the key to ensure a flawless result, Is to take all the time you need to open and reseal It.