I am assuming you cancelled the free 14 day cinema trial otherwise the cinema pass will keep auto renewing each month until you cancelled.
Should you wish to re subscribe to a nowtv cinema pass, then go to the nowtv website, click on My Account (or person symbol if using a mobile) enter your previous used existing nowtv account details then select Passes & Vouchers.
Hopefully you should see a Buy Pass button next to the cinema pass, click on it and your cinema pass should activate again.
Or alternatively if you want to save some money apply a cinema voucher code or gift card to your account rather than paying £9.99 per a month.
More info here about re subscribing again to nowtv.