The exegetical issues involved with this passage are too numerous to even begin to approach a detailed discussion and interaction with scholarship. However, these will be steered clear of while still attempting to discern if this passage contains the word-picture of repentance.
Three aspects of these verses could possibly portray the concept of repentance. (1) Does the concept of “bears fruit” allude to John the Baptist’s teaching in Matt 3:8? (2) Can the idea of being cleansed be related to repentance? (3) Does the phrase “apart from me” mean the opposite of repentance (turning away from God, not away from sin)?
The relationship between the Synoptic Gospels and the FG obviously can not be examined in detail at this time. Scholarship has mostly come to the consensus that the FG is independent. However, several commentaries link the author of the FG as being a disciple of John the Baptist (like Morris). This would leave the possibility that the author (and Jesus) could be drawing from John the Baptist’s words. While the phrase appears to be functioning in the same way with the same meaning (see discussion above under Matt 3:8), this appears to be too far of a stretch to put any significant weight upon.
Can kathairein be connected to repentance? In 15:2 it is used metaphorically, referring exclusively to pruning, with no moral or cultic imagery. But it is used differently in 15:3: here it does not, however, refer to conversion. The logon is the reason for the disciples’ purity. According to Bultmann, “this logos includes the forgiveness of sins, but does not refer specifically to it.” The theme of outward ritual purification (John 2:6; 3:35) may be held in contrast to this cleansing. The previous use of this word in the FG was at 13:10.
In 15:5, being “apart from” the vine is contextually the opposite of abiding. The idea of being apart from the vine contains slight connotations to being the opposite of repentance. Repentance is the turning away from sin and is demonstrated by bearing fruit (Matt 3:8); abiding is remaining in God and is demonstrated by bearing fruit. Regarding feron karpon in John 15, Bultmann says that it is not specifically missionary work, nor does it refer to success or reward; rather, “similarly to Mt. 3:8,” it “signifies the evidence for vitality of faith.” Abiding appears to be the other side of the same coin as repentance: abiding is loyalty, a remaining in God; repentance is turning away from sin. This final proposal is the most helpful one in seeing the concept of repentance in this passage. Again, repentance is linked with faith.