Replace the tub. I'm surprised you got 15 years out of it. Most don't get but 2-3.

Refinishing and reglazing are two different things. Reglaze requires it to be removed and taken somewhere that has an oven to bake the finish on...

We are remodeling our main bathroom. It has a cast iron tub with tile around it. We are not changing the tub but having it refinished. The company that is doing it offers a 15 year warranty. You can also buy touch up kits if you need it. I just called them and they said it can be refinished as many times as you want. Its just like painting a car. It would be stripped down and repainted.

I will be posting photos soon.

For us there is no option as to take out the tub would require taking down a wall or cutting the tub in pieces.
I am changing the color from a yellow from the 50's to white.

"Reglaze requires it to be removed and taken somewhere that has an oven to bake the finish on..."

Last time I went looking the only place that tried offering actual re-glazing was gone.

That leaves only one option, paint.
Epoxy based paints are pretty tough, but they still do not work well in bathtubs.

And even if the tub is removed and "baked" it takes a few thousand degrees to actually re-glaze (re-porcelain).
Anything else is just paint.

Hmm, thank you for setting me straight on reglazing vs refinishing. The most likely replacement tub would be acrylic. How is acrylic going to feel compared to the cast iron? Several years ago I built a house that came with those tubs that included a surround. I'm sure they were low end boulder grade but I thought they were acrylic and they were awful. Are good quality acrylics the same?