Sometimes it's a question of accounting, depending on how the budgets are managed, it might be difficult to justify spending on something for 3 years later, if there's no real requirement to do so.

Add a year each year (so it's an annual action item) but keep the expiry date at least 3 years away.

For some (family email, my email, super-vanity domain), I register them as far in advance as I can whenever they get close (ie <1y) to expiring. Just avoids hassles.