[header] How to use leftover dough or batter [title] Use batter within 24 hours. [step] Refrigerate any extra batter or dough, covered with plastic, for up to a day. [substeps] You won't want to use batter that is older than 24 hours. 
Most batter contains milk and eggs, which can spoil quickly if not used. Batter will also lose its leavening if its left too long.