I have a recurring infection from root canal on my front bottom tooth (done 20 yrs ago). is there any other treatment apart from removal of the tooth?

RCT failure: The treatment options depend upon two factors. First, the cause of the recurring infection. Some such as an incomplete fill can be retreated, while others such as a root fracture are hopeless. Second, one has to consider long term prognosis of any treatment and alternatives. A simple re-treatment or apico\retro by qualified Endodontist might do the trick. Ext and implant might be better choice.

See an endodontist: With proper care, even teeth that have had old root canal treatment can last a lifetime. An additional endodontic procedure may be able to support healing and save your tooth. If you have pain or discomfort in a previously treated tooth, talk to an endodontist about re-treatment.

Yes: Sometimes redoing the root canal treatment is helpful. In light of the methods, materials, and technology available today you should investigate the pretreatment route. Please make sure to see a specialist Endodontists who has equipment, training, and expertise not common in a GP's office.