I read that the target dose of rexulti for depression is 2mg/day and the max dose is 3mg/day. if one is already taking 2mg, would an increase to 2.5mg still provide therapeutic benefits, since it is above the target dose? thank you?

It is not possible to predict this because everybody is different in the effect medications have due to differences in absorption, metabolism, brain effects, etc. The best way to manage this is with the physician who prescribed the medication or by seeing a psychiatrist if it was prescribed by a different doctor. A psychiatrist could advise on whether an increase in dose is likely to help.