Question: "Why doesn't God give the fallen angels a chance to repent?"
Answer: The Bible does not specifically address the issue of fallen angels having an opportunity to repent, but we can gain some insight from what the Bible does say. First, Satan (Lucifer) was one of the highest angels, perhaps the highest (Ezekiel 28:14). Lucifer—and all the angels—were continually in God’s presence and had knowledge of the glory of God. Therefore, they had no excuse for rebelling against God and turning away from Him. They were not tempted. Lucifer and the other angels rebelling against God despite what they knew was the utmost evil.
Second, God did not provide a plan of redemption for the angels as He did for mankind. The fall of the human race necessitated an atoning sacrifice for sin, and God provided that sacrifice in Jesus Christ. In His grace, God redeemed the human race and brought glory to Himself.
No such sacrifice was planned for the angels. In addition, God referred to those angels who remain faithful to Him as His “elect angels” (1 Timothy 5:21). We know from the biblical doctrine of election that those whom God elects to salvation will be saved, and nothing can separate them from God’s love (Romans 8:38-39). Clearly, those angels who rebelled were not “elect angels” of God.
Finally, the Bible gives us no reason to believe that angels would repent even if God gave them the chance (1 Peter 5:8). The fallen angels seem completely devoted to opposing God and attacking God's people. The Bible says that the severity of God’s judgment varies according to how much knowledge a person possesses (Luke 12:48). The fallen angels, then, with the great knowledge they possessed, are greatly deserving of God’s wrath.