MacBook – I accidentally touched the rMBP screen with sweaty hands

No. The organic material is applied during assembly. I'm not aware of any place that can "replenish" the lipophobic substance.

Apple has this to say:

"Please note that the ability of this coating to repel oil will diminish over time with normal usage, and that rubbing the screen with an abrasive material will further diminish its effect and may scratch your screen."

Source: http://support.apple.com/kb/ht3226

You can, however look into replacement covers that also contain lipophobic properties: http://www.mobimega.com/sgp-steinheil-ultra-oleophobic-screen-protector-for-iphone-4.html

Or pay for a new glass screen. Warranty will generally not cover this, but you can always ask for a quote from Apple service in or out of coverage.

Rather than an exorcist, I'd take it to an Apple Store, because the keys should not repeat unless you let them pressed. There are various factors than can cause this behavior, but if the machine is relatively new, there shouldn't be any reason for this to happen. Most of the ideas come from a Software malfunction, some utility misbehaving or such.

I suggest you create a new user and work a few hours/days from there to see if it happens again. If it never happens, migrate your data to this new account and problem fixed. If it keeps happening, rush it to an appstore and see what happens. It's not common. Good luck!