Knowing the right way but choosing to do the wrong is to sin willfully.

You have repented of your sins and accepted Christ as your Saviour yet you continue to return to the past sins are also considered willful sinning.

It means that you disregard the sacrifice that Jesus has done for you and so the Lord will judge you harshly. Let us pray that we do not fall into this state.

For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins, but a certain fearful expectation of judgment, and fiery indignation which will devour the adversaries. (Hebrews 10:26-27)