I'll ask you the same question that I asked HeRose earlier. Do you believe that we have to get saved every time we sin?
If you have a process of sanctification you also require the ability to ignore certain behaviour because of the desire to follow Jesus. As Paul argues this is what made Abraham righteous, and likewise us.
Jesus's imputed righteousness if true, obviously implies you are saved for good, because if this righteousness is ones own righteousness, there is never any sin for judgement. If on the other hand, faith is reckoned as righteousness, it is the desire to follow and obey that keeps ones faith on track, no matter the stumbles. Peter stumbled in the denial of Jesus, yet Jesus prayed for his faith to hold strong, ie the relationship was founded on faith that produced obedience rather than Peter was forgiven no matter what.