I have bridge on 2 premolars and 1 molar. I have lost 2 molars. Is it good to leave as it is or is there an alternative?

Since you have lost 2 molars, your bridge extends from premolars to a
wisdom tooth (3rd molar).
Assuming that you can keep the area clean, this would work. Implants are another solution to replace the
molars. Unfortunately, when molars are extracted and implants are desired, one
has to look at where the sinuses are located and how much bone is available for
the implants. Lack of bone is not a
deterrent, but a separate sinus lift and bone grafting procedure may be
necessary. All things considered,
implants are preferred. If you select
implants, the premolar crowns should be replaced. Talk to a good restorative cosmetic dentist
to determine the best solution.

it is not advisable to leave as it is . long term with out restoration results in mal-aligment on other teeth. restore it as soon as possible. best option is dental implants.

Bridges are good , the only thing to consider is that the receeding bone will continue , and this can damage the adjacent teeth , which you need to preserve.dental implants can preserve the height of tjis areas , and you can have individually restored teeth.