Can we roll over existing futures position by 3 more months?

Can someone explain if we can extend the futures position by 3 more months if you are in loss?

You can. You will have to close position of Futures contract you are currently holding and then take position in expiry of your choice.

But if I close the position, I will incur loss which I want to avoid.

Futures are Marked-To-Market, you book loss/profit every day. So it doesn’t make any difference.