Short answer. Very likely yes. A conviction normally bars a second prosecution, but the rule carves out an exception where the graver offense developed because of supervening facts arising from the same act. A death occurring after your plea is the standard example of such a fact.
What the law says
the conviction of the accused shall not be a bar to another prosecution for an offense which necessarily includes the offense charged in the former complaint or information
Rule 117, Section 7 — Former conviction or acquittal; double jeopardy. Read the full provision →
What the law says
(a) the graver offense developed due to supervening facts arising from the same act or omission constituting the former charge
Rule 117, Section 7 — Former conviction or acquittal; double jeopardy. Read the full provision →
Why a conviction usually ends the matter
Ordinarily, once you have been convicted or acquitted, that judgment bars another prosecution not only for the offense charged but also for any attempt to commit it, its frustration, and any offense which necessarily includes or is necessarily included in the offense charged. That is the protection most people mean when they speak of double jeopardy. A graver charge built on the same act would normally be swallowed by that protection, because the lesser offense you pleaded to is necessarily included in it.
The supervening-facts exception, and why it fits this situation
The rule then removes one category from that protection. A conviction is not a bar to a prosecution for a graver offense where the graver offense developed due to supervening facts arising from the same act or omission constituting the former charge. The wording matters: the graver offense must have developed afterwards, out of the same act. A victim who was alive when you pleaded and who later died of those injuries is the situation this clause was written for. Nothing about your act changed; its consequence did.
What the exception does not cover
The exception is narrow, and two things fall outside it. First, it does not apply where the prosecutor simply reconsidered how to charge conduct that was already complete. If every fact making out the graver offense already existed and was already known when you entered your plea, the offense did not develop later. Second, the exception runs in one direction only: it permits a prosecution for an offense which necessarily includes the one you were convicted of. It is not a general licence to relitigate a closed case.
Time you have already served is credited
If you are prosecuted and convicted of the graver offense, the sentence you already began serving is not wasted. The rule provides that where the accused satisfies or serves in whole or in part the judgment, he shall be credited with the same in the event of conviction for the graver offense. That credit is written into the rule rather than left to the court's discretion, and it applies whether you served part of the term or satisfied the judgment in full. Whether the exception applies at all is fact-heavy and worth raising early.