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