Is it forbidden to falsely swear upon the Holy Quran to avoid killing a person or a major problem, and does repeatedly committing a sin, repenting from it, and then returning to it make a person a hypocrite?

Lying is forbidden and considered a major sin. If it is affirmed by an oath and placing one's hand on the Quran, its prohibition becomes even more severe, unless there is a legitimate Sharia interest that cannot be achieved except through it, such as repelling harm from a Muslim. Lying is permissible to avert murder or harm to one's honor and dignity, but it is not permissible if the harm can be repelled by using equivocation (Tawriya) or insinuation (Ta'rid).

As for repeating a sin after repentance, it does not invalidate the sincerity of the repentance according to most scholars. The validity of repentance depends on abandoning the sin, regretting it, and having a firm resolve not to repeat it. However, repentance or seeking forgiveness with the intention of repeating the sin is the state of hypocrites and is of no benefit.