2 Peter 1:15

10Therefore, brethren, be even more diligent to make your call and election sure, for if you do these things you will never stumble; 11for so an entrance will be supplied to you abundantly into the everlasting kingdom of our Lord and Savior Jesus Christ.

12For this reason I will not be negligent to remind you always of these things, though you know and are established in the present truth. 13Yes, I think it is right, as long as I am in this tent, to stir you up by reminding you, 14knowing that shortly I must put off my tent, just as our Lord Jesus Christ showed me. 15Moreover I will be careful to ensure that you always have a reminder of these things after my decease.

In verse 15, is he referring to his epistles, Mark's gospel or something else. How will he "be careful to ensure" (be diligent in the KJV). In verse 10 he encourages the Christians to "be even more diligent to make your call and election sure". As they "give sure diligence" with their calling, Peter will "give sure diligence" to always have the things of the Gospel "on their mind" so to speak. The question arises of how this will be accomplished after his "decease". Could this be a reference to some future action such as handing off a pastoral authority? 1 Clement may give some insight:

And thus preaching through countries and cities, they appointed the first-fruits [of their labours], having first proved them by the Spirit, to be bishops and deacons of those who should afterwards believe. Nor was this any new thing, since indeed many ages before it was written concerning bishops and deacons. For thus says the Scripture a certain place, "I will appoint their bishops s in righteousness, and their deacons in faith."

and

Our apostles also knew, through our Lord Jesus Christ, and there would be strife on account of the office of the episcopate. For this reason, therefore, inasmuch as they had obtained a perfect fore-knowledge of this, they appointed those [ministers] already mentioned, and afterwards gave instructions, that when these should fall asleep, other approved men should succeed them in their ministry