You've only been on it a month, so quitting shouldn't be a big deal. Still, this is the most difficult of all the antidepressants to stop taking, so just to be safe you should taper down off it and not go cold turkey.
I would quit the Paxil completely before starting again on the Lexapro. That way you can distinguish withdrawal symptoms from side effects of starting Lexapro -- sometimes going back on a drug is different than the first time you took it. Since you've only been on Paxil such a short time, this shouldn't be a big problem, just a safety precaution. I got your PM, and this is what I would have said there. My own view is, when you start a new drug while withdrawing from an old one you're really on two drugs at once in different stages -- too complicated for most psychiatrists to handle, so it's best not to confuse them!