I can think of 3 choices:
leave it alone and drink it
dilute post fermentation
blend with un-hopped (or low-hopped) similar recipe
What was the recipe? Depending on the strength (both alcohol and unfermentables like roast, chocolate, etc.) you might be able to just dilute after fermentation to get something sessionable. Or repeat the recipe with far less hope and blend. Certainly not the same beer as the recipe intended, but still something...