Returning to Taiwan, hopefully

I would really like to return to Taiwan to teach and I was wondering what the best way to that would be in terms of obtaining a visa. My passport currently has an ARC sticker in it from when I was studying Chinese as well as a working visa sticker from when I started teaching after studying. I’m nervous about paying for the roundtrip ticket and then being denied a visa back into the country. I would really like to return and study and teach again. Does anyone have any suggestions as to how to best obtain a new visa?

You say you have an ARC sticker, but is your ARC still valid ? I’m guessing not, they will know this when they check your passport at immigration.
You’ve have to do what you did last time.

Loose your passport and start fresh!

I don’t see what your problem is. Just go and apply for a visa.