Hi Natraj.

If you're not allotted any seat in round 1 of CAP, you don't need to visit any registration centre. You only need to do that once an option is allotted to you. What you can do is you can make changes in your choices, if you want. you have to wait for next round of allotment, when you may get a seat allotted depending on the availability of seat.

Good Luck.