Synonyms for Conserve (same or very similar meaning)
WordNet sense 1 (fruit preserved by cooking with sugar):
preserve, preserves, conservesWordNet sense 2 (keep in safety and protect from harm, decay, loss, or destruction):
maintain, keep upWordNet sense 3 (use cautiously and frugally):
economize, husband, economiseFrom the ODE community, based on WordNetadd/edit