Yes, arrancars(most of them) had only one chance to regen and that was when they unleashd their real body's. After all it's called a resurrection ;P.
The one that opened the senkai gate was Ishin. Ichigo didn't and still don't know how to do it(Ishin knows because he is from soul society(it was stated in one of the interviews)).
Here's the pic:Spoiler!