No.
FAQ: "The hex acts like the appropriate cure wounds spell, so it damages undead.
When used this to damage undead, it should have the same once-per-24-hours limitation as its healing usage (even though that's not a "benefit" to the targeted undead).
For clarity, where the hex currently says:
"Once a creature has benefited from the healing hex, it cannot benefit from it again for 24 hours."
It should actually say:
"Once a creature has been affected by the hex, it cannot be affected by it again for 24 hours."
This will be updated in the next printing of the APG."
If you fail to hit with a touch attack, you can be considered to be holding the charge, and can try again.
If the undead creature saves against the cure, and takes half damage, the Accursed Hex would appear to allow you to try again:
When you target a creature with a hex that cannot target the same creature more than once per day, and that creature succeeds at its saving throw against the hex’s effect, you can target the creature with the same hex a second time before the end of your next turn. If the second attempt fails, you can make no further attempts to target that creature with the same hex for 1 day.
It doesn't say "If the hex fails to affect the creature" but "the creature succeeds at its saving throw". An undead who saves against the CLW effect of the healing hex and takes half damage has "succeeded at its saving throw against the hex's effect" and therefore allows you to use the hex again the next round.
Edit: this would also appear to make it beneficial for an ally to attempt to save against the CLW effect in the first attempt, because then you could use the CLW effect on them again. Hmm.
No, but it does appear to be the effect of the written rule.