Tu as ta réponse directement dans ton lien de Apprendre de ses erreurs, dans la partie FAQ :
Q: If I fail a test that has costs other than actions associated with it (like spending ammo or charges), do I need to respend costs to 'attempt that test again'? My read is no: it's not a new action, it's just 'go straight back into the skill test', without spending costs. Is that correct?
A: Correct. The investigator does not need to pay any costs associated with the skill test again (such as ammo, actions spent, etc), although anything spent to improve the previous test (like committed costs or resources on a Talent) are indeed lost at the end of the first test.
En français, tous les coûts restent; par contre, si tu avais attribué des cartes au test, les bonus sont perdus.