If there is a hint of doubt held by any baptized member of the church, why would any right-thinking and charitable soul refuse them the right to be re-baptized? Now, I've suggested the Alma exception and how that might be accomplished in a time of reluctance and resistance to recommitment baptism. But it occurs to me upon further reflection that since the church doesn't recognize or record rebaptisms anyway, why would this concern the "heavy laden priesthood" which has no time for such things? Anyone holding authority, at any place where there is sufficient water to perform the rite, could accomplish it. Since the church doesn't record it, there is no need of witnesses. It could be done in private, at any time, or any place with sufficient water. It could be done by any person holding the office of Priest. It would be good practice for future missionaries if they were given the opportunity. I think the idea is one which ought to be acted upon with regularity, in private and without troubling the busy and overburdened church and priesthood. A close family member could take care of it, and I suspect all involved will soon recognize heaven's approval of the idea.]
Well, back to the subject at hand. Anciently the Jews practiced baptism in "living water." That is, in a naturally renewing body of water, like a river, lake or ocean. Living water was part of the symbol. We have fonts, and there is nothing wrong with that. But I have always cherished my baptism in the Atlantic Ocean.
What does it mean to "inherit the kingdom of God?" Would that be important to secure while alive? This work cannot be done after death, you know. (D&C 138: 33.) However, if offered the opportunity now and a person declines it, they cannot afterwards receive it and inherit the "kingdom of God." They inherit another kingdom. (D&C 76: 74.)