“New” = καινηνG2537 A-ASF, not “neos” (G3501).
Jesus demonstrated love in action, in truth, the pharisees had only love in theory, in hypocrisy.
Here is how John, himself, understood it:
1Jn 2:1 My little children, these things write I unto you, that ye sin not [1 John 3:4]. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous:
1Jn 2:2 And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world.
1Jn 2:3 And hereby we do know that we know him, if we keep his commandments.
1Jn 2:4 He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.
1Jn_2:7 Brethren, I write no new commandment unto you, but an old commandment which ye had from the beginning. The old commandment is the word which ye have heard from the beginning.
1Jn_2:8 Again, a new commandment I write unto you, which thing is true in him and in you: because the darkness is past, and the true light now shineth.
2Jn 1:9 Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.
2Jn_1:5 And now I beseech thee, lady, not as though I wrote a new commandment unto thee, but that which we had from the beginning, that we love one another.
Thus the ‘old commandment’, they had from the beginning, was seen in the face of Jesus Christ, as they had never understood it before:
Exo 20:6 And shewing mercy unto thousands of them that love me, and keep my commandments.
2Co 4:6 For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ.
Jesus magnifies the law, and magnification, removes not one part, but demonstrates the deepness of it:
Isa 42:21 The LORD is well pleased for his righteousness’ sake; he will magnify the law, and make it honourable.
Psa_119:96 I have seen an end of all perfection: but thy commandment is exceeding broad.