Don't Oxygenate Now! you don't want to risk off-flavors caused by it.
That said, here's 2 questions, and 2 solutions:
1) What was your OG?
2) What strain yeast are you using?
Here's what you can try:
1. Slightly rouse the yeast. Give the fermenter a good rock to raise the yeast off the bottom and maybe get them to freshen up a bit.
2. Re-pitch. Either after racking to a secondary, then taking a bit of the yeast cake and making a new starter + nutrients (say, 1500mL), or take a new vial/smack-pack and make a new starter + nutrients (again say, 1500mL).
I just went through option 2. myself last week, after having my Double-dubbel stall out at 1.055 (1.107OG). Now it's at 1.038 today. woo woo!
Hope that helps.
Primary: Stone Vertical Epic 08.08.08
Secondary: Oaked Arrogant Bastard
Conditioning: Dead Guy Ale clone, Double-Dubbel
Drinking: Not for a while