H1b transfer?

Hi Friends,

I am now working at a private company with an H1b visa, and would like to go
back to university for a postdoc position. I have a question about H1B
transfer.

If I want to go back to industrial areas later, should I have to apply for a
new H1B (Cap limited, for industrial one) and wait until Oct. 1 to start to
work? or I just need to renew my previous H1b (industrial) and start to
work right away?

Thanks in advance!