Landing distance should be corrected for any speed increment above Vref, which is planned or expected at the threshold. Most manufacturers provide corrected distances for failures / abnormal configuration, icing, and may also provide correction for thrust reverse, brake setting, and speed excess.
A general rule of thumb for speed excess is 300 ft per 10 kts on a dry runway and 500 ft per 10 kts on a wet runway (
AC 91 79 Runway Overrun Prevention).
However as JT states, providing you can avoid floating which might be more difficult with increased speed.
The distance penalty for floating is very high; 2500 ft per 10kts; also or alternatively consider any delay in touchdown; 230 ft per sec.
So a simple 10 kts excess could easily add an extra 3000 ft to the actual landing distance.