In the example of the various kinds of seed and ground - the "seed springs to life" then is choked out. There is nothing there about "springs to life and so no possibility of dying" in that illustration.
So also in Matthew 18 in the "forgiveness revoked" example the statement is made "I forgave you all that debt because you pleaded with me..." and then the command given to return all the former debt. Nothing there about "I forgave you all that debt so no chance that it will be returned to you".
In Romans 11 you have the statement "you stand only by your faith" followed by "you should fear for if God did not spare them he may not spare you either" - in its appeal for "perseverance".
All of these - and many more like them appeal to the already forgiven, already saved, already born-again saint to "persevere" arguing that failure to do so would be to lose their state. For example they would become "severed from Christ, fallen from grace" as we see in Galatians 5.
The lost cannot "fall" -- they are already fallen.
Interpreting the parable of the sower is the crux of the whole matter to me. Those plants are all believers when first given the Gospel. Their races of faith fail in most cases though. The ones with shallow root seem to lack a heartfelt faith and fall away when the going gets tough. The believers choked by weeds also seem to lack genuine faith and let the world rob them of salvation in exchange for a good life in this world. The thing is am I interpreting this wrong? Do these people lack a genuine faith or are they Spirit filled believers gone astray to hell? I believe it is the former now given Ephesians 1:13-14 and Hebrews 10:14. The problem is not that these people are genuine and fell away, but that they were never genuine in the first place and testing revealed this.