Sounds like it is likely too late to adjust your OG at this point (assuming that OG you posted was a reading you took of your wort). You would need to raise it to obtain a higher ABV in the end, basically more sugar in the wort. If you post the recipe you are brewing im sure plenty of people will have good suggestions on how to tweak it!
Although I never do either of these. To get the OG down, just boil and cool more water and dilute it. If you need it up, just add some boiled sugar (DME, honey, cane sugar, etc.). If you have DME, just use that. Again, I still wouldn't do it. When I first started brewing, I thought higher alcohol was better. Now, I brew completely for flavor/style with an average amount of alcohol. I only really check gravity readings to determine my fermentation. I log them, but sometimes I forget.
My problem is that everything I have has too much alcohol. I keep drinking commercial because I don't want to get trashed.
I've done an APA that came in at 5.8%, but apart from that, all the beers I made this year have been 8 or 9% (Belgians, Wee Heavy, Robust Porter, and more Belgians). Going to get down to making some reasonable strength Pale Ales.