It can be done. I'm not saying change the baseline basher into a slice and dice serve and volleyer. Throwing in a slice, a high heavy or a drop shot in appropriate situations works. Variety can also be done through momentum management, applying base game/consistent play or playing offensive/going for it based on the score and what happened during the previous point subtly creates variety and can keep an opponent off balance with them even knowing what's hit them.
I watched Borna step up a serve and volley followed by a baseline ralley followed by a drop shot in the next rally then back to baseline rally's for a while then back to mixing , he was very good at it , his coach did a great job , we are gonna try and incorporate more in out game as should the Original Poster.