What everyone has said here is excellent: let me add another thought…
In 1 John 1:9, we are told that if we might ὁμολογῶμεν (‘homologomen’) our sins, then Jesus might forgive our sin. To translate the word ὁμολογῶμεν as “confess” is somewhat problematic. In an archaic context, it’s a perfectly fine translation; in that context, it would be reasonable to say, “I confess that this is a beer that I’m drinking” or “I confess that these jeans I’m wearing are pretty grungy.” However, in that usage, we’re not talking confession in the sense that Catholics use it – that is, in the context of the sacrament of reconciliation. Rather, this sort of ‘confession’ really is just an acknowledgement – “yeah, this is a beer” or “yeah, I probably should’ve worn a clean pair a jeans.”
So, the context of 1 John 1:8-9 is a juxtaposition of opposites: either we say “I have no sin” or we say “I acknowledge my sins.” In one case, denial of sin shows that we deceive even ourselves; but in the other, acknowledgement of sin indicates that we are open to Christ and the possibility of forgiveness. What this verse isn’t talking about is an action that we take (namely, a verbal (or even non-verbal) prayer requesting forgiveness!). So, if your friend wants to use 1 John 1:9 as proof that we can take the action of praying for forgiveness, then she’s missing the point of this verse of Scripture.
One other note: verb tense is important here. In these verses, we aren’t seeing a command (“confess your sins!”) or even an indicative statement (“we confess our sins”); rather, it’s in the subjunctive mood, so it’s expressing probability. Wallace, in Greek Grammar Beyond the Basics, indicates that this appears to be an instance of a “consecutive or ecbatic” use of the conjunction ἵνα (‘hina’, meaning “so that” or “with the result that”). What Wallace means here is that we have two verbs: the main verb (“we might acknowledge”) and the verb attached to ἵνα (“he might forgive us”). Now, the ἵνα verb is a result, but it’s not an intended result: in other words, we don’t do the main verb in order that the ἵνα verb might occur – instead, we do the main verb, and the ἵνα verb just happens to occur. It’s kind of like saying that I drove to the mall, and as a result, I got a flat tire. I didn’t intend it – in fact, that wasn’t in my mind at all – but it happened nevertheless. (cf Wallace, 1996, p 473).
So, if this is true, then it really hurts your friend’s case. After all, what the inspired writer isn’t saying is “confess your sins with the intent of receiving forgiveness,” but rather, “if you confess your sins, guess what? Jesus might just forgive you!”. That’s hardly the kind of statement that leads to confidence! Rather, John 20:23 is exactly the kind of action-result statement that we’re looking for – when someone with apostolic authority forgives sins, these sins are unequivocally forgiven by Jesus!
Hope this helps…!