if you have a credit card added to the account and didn't turn off the auto renewal option it renews automatically and charges the card if you didn't add a card or turned off the option to auto renew you can log into your account at store.sonyentertainmentnetwork.com and access the store then buy a new membership , games or anything else you want by adding funds with a credit card or psn card the new ps4 will have the same account when you sign in and any time you have on the membership will still be there .
The information is on your PSN account, ONLINE, NOT on the PS4 itself. So whatever you did last time, it's all there, still saved on your PSN account ONLINE. So you just have to sign in to your PSN account and you're set.