One more thing, she could also be trying to say "my whole life" [一生] out loud, since it also starts with the same sound. [phonetically identical characters]
I'll update the TL note page when I'll have access to my PC again.
Pretty sure she’s talking future tense, like she WILL keep making bento. Thus the “my whole life” she’s thinking. She’s saying it doesn’t matter how many get destroyed because she’ll keep making more and is just hesitant about phrasing it in a way that sounds like a proposal.