Guys,
I recently moved from my hometown, which sits at 960 meters above the sea level to another city which is at 2640 m.a.s.l.

I've noticed my lack of air specially when climbing to a local mountain with a peak altitude of 3100 m.a.s.l. Is there a way to regain fitness/adapt to the new altitude? I've been riding for a couple of months but I am nowhere near my fitness level I enjoyed when I lived in my hometown.

Thanks in advance!

I've heard it takes some time for your body/lungs to adapt, due to the lower air pressure? I would become familiar with altitude sickness and also look into altitude acclimatization or adaptation.

You will eventually adapt. Your body will produce more blood cells and capillaries will adjust to the pressure and not burst (headaches).

Drink plenty of water, avoid alcohol and caffeine and carbonated drinks.

What cd said - more information here:
https://www.altitude.org/altitude_training.htm

You will never be as fast at a higher altitude as at a lower. There's less oxygen. However, your performance at your old, lower altitude will now be somewhat improved over what it was. As the article states, you would get more benefit at all altitudes by driving to a lower altitude to train.

I find I get noticeable benefit from spending as little as 24-48 hrs. at over 3000m.

2 weeks