The permit and the card are two different things. A permanent permit applies without a time limit, but the physical residence permit card (UT-kort) must be renewed when it expires. So it is the card, not your right to stay, that lapses.
- For permanent residents the UT-kort is valid for 5 years, according to Migrationsverket — do not rely on third-party sites that state 3 years.
- About 3 months before the card expires you are notified via Min sida.
- You book a time to be re-photographed and give fingerprints, because the biometrics are on the card's chip.
- Bring a valid ID document and your current card.
Renewing the card is an identity and biometrics update, not a re-assessment of your right to stay. The card's validity period can change, so check the current procedure with Migrationsverket.
Sources
Official details can change. Always confirm what applies to your own case directly with the responsible authority.