i had to leave my dd to dry at around that age as it took longer and longer each night to get her down, and then she wouldn't stay down. it's up to you, don't do it if you're not sure you can follow through though as it'll only make the situation worse.
if you do do it though it should only take 2 nights or so before she gets the hint. i left dd but went in when things went quiet to check she was ok and straighten her out. if she wakes up i go in, tuck her in with a 'night night' and walk out again, that way she knows i'm there but she's not getting up.