Ran out of hair dye, now what?

Yesterday, I tried to dye my hair brown over my previous red colour and I ran out of dye. So now I have parts that are still red. Can I dye the whole head so soon, or do I need to dye only the pieces that are lighter? Do I need to go to a salon to correct this? I don't want to burn my hair, it's sensitive

Ran out of hair dye, now what?
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