Short answer. No. Article 1425 provides that when a third person pays your already-prescribed debt without your knowledge or against your will, and you later voluntarily reimburse that person, you cannot recover what you paid. Your voluntary reimbursement is treated as final, even though you were no longer legally bound to pay.
What the law says
When without the knowledge or against the will of the debtor, a third person pays a debt which the obligor is not legally bound to pay because the action thereon has prescribed, but the debtor later voluntarily reimburses the third person, the obligor cannot recover what he has paid.
Civil Code, Article 1425 — Third-Person Payment of a Prescribed Debt. Read the full provision →
Voluntary reimbursement cannot be undone
Article 1425 addresses exactly this sequence of events. It provides that when without the knowledge or against the will of the debtor, a third person pays a debt which the obligor is not legally bound to pay because the action thereon has prescribed, but the debtor later voluntarily reimburses the third person, the obligor cannot recover what he has paid. Because your friend paid the debt without your knowledge, and you were legally free to refuse to pay it since the action to collect had already prescribed, your choice to reimburse your friend anyway is treated as a final, deliberate act, not something you can later reverse.
Why prescription did not obligate you to reimburse
Prescription bars the creditor's action to collect the debt, and by extension it affects a third person who pays it on your behalf without your involvement; you were never legally required to reimburse your friend for covering it. Nothing in the law compelled you to pay your friend back once you found out. The reimbursement was your own voluntary act, made with the freedom to have simply declined.
Why voluntary payment still binds you
The law generally does not let someone take back a payment made voluntarily and knowingly, even where the underlying obligation was not legally enforceable, because the whole point of prescription is to give the debtor the option to invoke it or not. Choosing to honor a moral or personal sense of obligation to your friend by reimbursing them, rather than invoking prescription as a shield, is a choice the law respects and treats as final once made.
What this means for your reimbursement
If you knowingly and voluntarily reimbursed your friend for a debt you were aware had already prescribed, Article 1425 forecloses any attempt to recover that reimbursement later. The key facts are that your friend paid without your knowledge or against your will in the first place, and that your later reimbursement to them was a free, voluntary choice rather than something forced or mistaken.