Or you do what El-Al does, you equip your 737th with chaff and flare.
These measures are, at best, somewhat effective in dealing with a isolated attack using a first and second generation MANPADS. Third and fourth generation systems now in military use are limited only by warhead size as far as killing a large non-maneuvering target like an airliner.
Larger missile systems like the Buk/SA-11, Patriot, or SM-2 have a Pk greater than 0.5 against small military jets with chaff, flares, RWR, ECM, EECM, etc. that can maneuver at or above human G limits. Current military doctrine combines careful route planning, terrain masking, stealth and mutual support to avoid highly capable systems whenever possible. Any airliner operating within the engagement zone survives only if the missile operator chooses NOT to fire.
Questions about how to design aircraft to survive missile attacks have resulted in the A-10 and SU-25 designs. The economics of operating either the single A-10B or the few remaining Su-25UBs as a single passenger aircraft are intuitively obvious.