Modify panel > Make a selection > Modifier List > Object-Space Modifiers > Array > UV rolloutThe Array modifier's UV rollout lets you control how UVs are applied to the clones in the selected array.

Sets the UV method.
(Default) No changes are made to the clones' UVs.
Maps the X, Y, Z direction values to UVW values for the corresponding clone's UWV map.
Applies the clone number to the UVW values of the corresponding clone's UWV map.
Sets the UV map channel where the UVW values are applied.
When enabled, UVW values are normalized from 0 .0 to 1.0, based on the following:
When enabled, adds the UVW values to existing values from the source map.
Sets the source UV map channel when the UV Method is set to Additive.