After being told to no longer speak in the name of Jesus, Peter and John were released. And so what did they do? They prayed for more boldness to preach the gospel. They said, "And now, O Lord, hear their threats, and give us, your servants, great boldness in preaching your word. Stretch out your hand with healing power; may miraculous signs and wonders be done through the name of your holy servant Jesus" (Acts 4:29–30).
Then the Bible tells us that after they had prayed, "the meeting place shook, and they were all filled with the Holy Spirit. Then they preached the word of God with boldness" (verse 31).
The Holy Spirit was poured out on the Day of Pentecost, but the apostles were given a refill. (And God does give refills.) Now we don't need another Pentecost, but we do need to continually appropriate what has been made available for us at Pentecost.
For instance, when you are in a restaurant, you may order iced tea, and after a while, the server will come and offer you a refill. So you get a refill. In the same way, God wants to refill you with His Holy Spirit.
There is nothing wrong with asking God for a refill. There is nothing wrong with praying, "Lord, fill me with the Spirit." In fact, there is something right about praying this, because we are told in Ephesians 5:18 to be filled with the Spirit: "Don't be drunk with wine, because that will ruin your life. Instead, be filled with the Holy Spirit." In the original language, that could be translated, "Be constantly filled with the Spirit again and again and again."
God will empower us with the Holy Spirit and fill us again and again and again.