No. Confession is honesty with a Father who already forgave you, not a payment that re-buys forgiveness you lost. You are not one unremembered sin away from falling out of grace.
The Grace Answer
This fear usually grows out of one verse taught as a maintenance routine: “If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.” Somewhere it got turned into a spiritual accounting system. Sin, then confess, or the forgiveness switches off. Sleep on an unconfessed sin, and you are exposed. That reading turns the Christian life into anxious bookkeeping, always afraid you missed one.
Look at who John is writing to and why. His whole letter is built to give believers assurance, not to put them on probation. When he says God is faithful and just to forgive, the word just is the giveaway. God is not forgiving you again from scratch each time. He is being just to the payment His Son already made. The debt was settled at the cross, so of course He forgives, He would be unjust to charge you twice for what Christ already covered.
So what is confession for?
The word simply means to agree, to say the same thing God says. Confession is not you generating fresh forgiveness by naming sins fast enough. It is you stepping back into the light and agreeing with God about what is true, including the truth that you are already clean. It restores your sense of nearness. It was never holding your salvation together.
Think about what the other reading would require. You would need perfect memory of every wrong thought and word, or you would die with unconfessed sin on the books. That is not New Covenant grace. That is a heavier yoke than the law ever was. Hebrews already told you the good news: “their sins and their lawless deeds I will remember no more.” You confess because you are forgiven, freely and honestly, not to keep from losing what you cannot lose.