Sudden night accidents. Shall i put nappy back?

[AnnamariaHun]

Hi everyone
pottytrained ds (will be 3 yo next month) in may and within about 3 weeks he was all clear and decided that he didn't want nappy at nights and has been dry ever since (he has been waking up at night for a wee)
in the last couple of weeks during the day he just can't be bothered to go to the toilet and keeps holding it but doesn't actually have an accidents just slowly his pants just get more and more wet.
at nights, he stopped waking up and when i go in in the morning i can feel that his sheet is wet so he didn't even wake up for it.
i started to go back to rewarding him when he tells me and giving him treats but at night he still wees without waking up.
Should i put him back in his nappy at night??
it's just annoying as i know he is capable of waking up but it just seems that he doesn't care any more about staying dry. (even when i leave him in his wet pant's he is fine with it)

Any advice would be appreciated

thanks