The expression "mixing it up" implies a change, a variation or a combination of different elements. There are several synonyms for this term that can be used in different contexts. For instance, "shaking things up" is a great alternative that implies a major disruption to the norm. Another similar expression is "changing things up", which is a gentler way of indicating a modification or adjustment. "Spicing things up" can be used in specific situations where there is a need for added excitement or interest. "Blending" or "combining" may be used to describe the act of putting things together or achieving a balanced mix. Overall, these synonyms help to convey the idea of something new and different being introduced to a situation.