You can try adding a TeX-command with this:

(eval-after-load "context"

  '(setq TeX-command-list

    (append

      '(

        ("context"

"context --purgeall %t"

          TeX-run-command t :help "Run context (MarkIV)")

        ("luametatex"

"context --purgeall %t"

          TeX-run-command t :help "Run context (LMTX)")

      ) TeX-command-list

    )

  )

  )

--

Mauricio Reyna