If your attorney dies and there are no other attorneys or replacement attorneys appointed, then you could if you still had the capacity make a new LPA. If however, you had lost capacity, you would have no attorney and an application would have to be made to the Court of Protection to appoint a Deputy to deal with your financial affairs.
If your attorney dies and there are other attorneys appointed in your LPA, whether the surviving attorneys can act will depend upon how they were appointed.
If they were appointed jointly, the surviving attorney(s) cannot act.
If they were appointed jointly and severally, the surviving attorney(s) can act.