Lager Fermentation Question

Regarding my first all grain recipe and my first lager:

I didn't hit the efficiency I was hoping for during the mash, and the OG fell a bit short of what I wanted. The beer fermented for about 2.5 weeks at 50F, then 3 days at 68F, and has since been at 40F for about 4 weeks. Its at about 4.5%, which is just flat out way too low.

My question: Can I bring it back up to about 50F and add some dry extract (dissolved and boiled and cooled, of course) and let it ferment again? Would that undo the 4 weeks of lagering that I've done?

4.5% ABV is within the BJCP style guidelines for a lager (2.8% - 6% depending on light, amber, dark) why do you think it's way too low?

I wouldn't add anything...I think some of the yeast would probably wake up and ferment the sugars but I believe you'd have to go through the lagering phase again since all of that yeast would be back up in suspension. I'm not sure how you would calculate how much DME to add either since you'd have unknown yeast activity and attenuation.

Just my thoughts....it sounds like it would be fine the way it is and you can always use the learning for the next lager your brew to get it up higher if that's what you're shooting for.

Good Luck!

The yeast suspension is the problem I was worried about. I agree with you that I'd have to lager it all over again, but I definitely wanted a second opinion about it. And there's nothing wrong with 4.5% according to BJCP, but as a rule of my own, I never aim for below 5% (I usually aim for about 7% for most of the ales I've done). This is for a family reunion in 4 weeks, so I can't afford to re-lager this batch.

Luckily, though, I accounted for the probability that I'd screw something up my first time brewing All Grain, and I brewed a similar recipe with extract as a backup.

Thanks for the advice. Anyone else have any thoughts? Agree/disagree?

IMO fooling around with this beer would be a big mistake. It's done. It's fine. Learn what you can and change whatever you need to for the next one.

It ain't broke, so don't fix it.

Also...some more details will help others give you better advice. Beer style? Target OG? Actual? FG? Mash schedule? Yeast?

I'd go with leaving it as is. I'm sure your beer is fine at 4.5%. remember that, while you would prefer your beers to be above 5%, not everyone does. And if this is for family, I'm sure some of them would appreciate the lower gravity beer.

I have Munich Helles which is 4.7% ABV and its good beer. Don't mess with yours, if you add more fermentables and fresh yeast in keg (I've done it several times to get rid of diacetyl) it will take about week to fully ferment, than you basically have to lager it again to drop that yeast out of suspension and you looking at additional 2 weeks. Is it worth it for extra 0.5-1% of gain? I don't think so. Enjoy your brew and adjust in future accordingly

Agreed. Thanks for the input everyone. I suppose I'll just have to adjust my recipes to account for my efficiency in the future (which I have yet to calculate haha).