Can you raise your sg after fermintation starts

I am trying a yuengling lager clone and At first my og was way to high so i added some water and well i over did it my og is 1.037 and i want it to be higher can i mash a few pounds of grains and add that to the mix or some extract . the majority of the grain bill was pils malt . thanks al

Your best bet at this point is to mix some extra light extract with a little boiling water, cool it and add it to the ferment. Since it's a lager, you have plenty of time. If you don't want to increase the batch volume, draw off some of the wort & fortify it.

It's quite acceptable to add more sugar to a batch during fermentation. that's a better way to get really high alcohol beer (the ones upward of twenty percent) - gradually ramp up the concentration of fermentable sugars. When you do what david_42 suggested, pay particular attention to where he said *a little boiling water* because you want the stuff you're adding to be of significantly higher gravity than your fermenting wort to make sure it raises it to your target gravity. That might be painfully obvious, but i just wanted to reiterate it just in case.