Now thats a tricky one, the ideal place to get another axolotl is through someone here in the for sale section,or the wanted section, that way you would hopefully no your axolotl's history. Alternatevly if you see some in a pet shop, check their set up. If the axolotl look well and healthy , i.e have gills with feathers and not pointing forward, all their limbs there and the shop tank is not over crowded or mixed up with other animals .Also try to get a similar size to your current axolotl, this will stop one being bullied more or even chewed ( or worse!) I would visit them a few times to check them out and that they are still looking good. If thats the case that alls well then select your animal. Bare in mind however that you will need to quarintine any new axolotl that you purchase. This is to make sure that it stays healthy and does not infect your current axolotl , there have been posts on this forum telling of the heartache that has been caused by not quarintineing ( wish I could spell!!) . Hoipe this helps!!
p.s you have a different icon on your message...don't have that one here...hurumphhh!