It is about salvation also known as born again of the Spirit. They testify to the promise from Jesus that we would never seek to be filled again as in never hungering nor thirsting. We are new creature in Christ and thus always Spirit-filled so we can be held accountable for what we sow towards, the fruits of the Spirit or the works of the flesh. We are not leaky vessels that need a continual filling. Here is another reference to why there can be no more filling because that would look like the Father was evil because He did not give you the Holy Spirit the first time as promised at your salvation for knocking at the door of Jesus Christ.
Luke 11:9 And I say unto you, Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you. 10 For every one that asketh receiveth; and he that seeketh findeth; and to him that knocketh it shall be opened. 11 If a son shall ask bread of any of you that is a father, will he give him a stone? or if he ask a fish, will he for a fish give him a serpent? 12 Or if he shall ask an egg, will he offer him a scorpion? 13 If ye then, being evil, know how to give good gifts unto your children: how much more shall your heavenly Father give the Holy Spirit to them that ask him?
John 6:35 And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst.
Matthew 9:17 Neither do men put new wine into old bottles: else the bottles break, and the wine runneth out, and the bottles perish: but they put new wine into new bottles, and both are preserved.
So apply those verses to the promise at our salvation and may He help you to see that our always being Spirit-filled is God's testimony in us that He has saved us. And that is why there are no other times for a saved believer to receive the Holy Spirit to avoid giving another calling, preaching another Jesus, another spirit , and another gospel.
2 Corinthians 11:3 But I fear, lest by any means, as the serpent beguiled Eve through his subtilty, so your minds should be corrupted from the simplicity that is in Christ. 4 For if he that cometh preacheth another Jesus, whom we have not preached, or if ye receive another spirit, which ye have not received, or another gospel, which ye have not accepted, ye might well bear with him.
Beware, brother.