There is a repeat synth sure it's having to go through recipes then starting it, but it sure beats having to go into the inventory as click on each item before each synth. Abort synth isn't really needed either, if you are so sure your synth will fail then just perform a rapid synth, if it succeeds you lose no durability, if it fails you lose a lot of durability so even when all hope is lost just go rapid and get it over with lol. I've had times where I thought my synth would fail only to get by through a rapid synth, so even if things look bad just go for it lol.

The only reason why we have a repeat function during leves is because of it's limited amount of synths ranging from 4-8. As mentioned earlier some things are increasing with this upcoming VU hopefully or maybe not until 1.22a but I doubt we'll ever get a true "repeat" function when it comes to our own materials.