There are several synonyms that can be used in place of the phrase "last time" to add variety and nuance to your writing or conversations. Some common options include "previously," "prior," "formerly," and "recently." Other possible synonyms include "antecedently," "once before," "in the past," and "in the prior instance." Depending on the context and tone of your writing, you may also want to consider using more colorful or descriptive synonyms such as "the final occasion," "the previous instance," or "the most recent event." Regardless of which synonym you choose, using different phrases to convey the same meaning can help keep your writing fresh and engaging.