I had veneers on my lateral incisor and the teeth are whiter than the rest so it stands out. What can I do to fix this?

Replacement is the only option. Get it done with an excellent cosmetic dentist.
Searching good cosmetic dentist is a very critical procedure. It's my advice to search good cosmetic dentist in your location and consult the dentist.

Hi Sartaaja...you are happy with your 4 month old veneer with the exception of the color.  Best solution is to whiten the rest of your teeth in the dental office and do the take home trays as well.  This will bring your other teeth up to the shade of the veneer and all will look white and match!  Easy solution. I would NOT replace a perfectly good veneer!  Whiten Whiten Whiten!

Having a single anterior veneer match perfectly is extremely difficult to accomplish.  Your two options are bleaching your other teeth since the veneer is lighter or replace the veneer.