I know that the magus spellstrike causes spells to crit if the weapon does, but does the same apply to spell like abilities applied through a conductive weapon?
Additional Damage Dice: Some magic weapons deal additional dice of damage. Unlike other modifiers to damage, additional dice of damage are not multiplied when the attacker scores a critical hit.
Magic Weapons and Critical Hits: Some weapon qualities and some specific weapons have an extra effect on a critical hit. This special effect also functions against creatures not normally subject to critical hits. On a successful critical roll, apply the special effect, but do not multiply the weapon’s regular damage.
Generally speaking, yes, certain extra effects do apply on criticals (such as Flaming Burst), but no they are not multiplied on critical.
Conductive Weapon Enchant affects SLA's and Supernatural abilities, not Spells. Magus Spellstrike specifically only affects Spells from the Magus Spell List and with range of Touch.
In the case of Magus using an SLA thru a Conductive Weapon, Spellstrike would not apply, but I would also say No to the Conductive SLA/Su dmg being multiplied on a critical, because it would be considered Additional Damage Dice from an Enchantment in the Magic Weapon general rules.
I agree with Ryze Kuja.
In addition, I would like to point out that the damage is not automatically delivered when the weapon strikes your target. The character has to make a conscious decision at the moment of impact to trigger the ability. Missing the target does not expend the uses.