Conditional repetition

Hello, I have a question, to see if anyone is so kind to answer it.
I have a piano part that repeats with repeating bars (2 times), at the top a melodic cello line and I want it to be repeated only the second time.
I have tried to put the repeat box (2nd) and it does not work.
Is there any way to do it? it's possible?

One way would be to duplicate the piano and only part of the cello but I wanted to do it with bars.
Thank you.