I assume you mean hour building from PPL up to 150 hrs prior to CPL following a modular route.
If so, you should use that time to get yourself ready for your CPL course. Speak to the school where you intend to do your CPL and get a structured hour-building progamme, practising the skills you will need. Also, familiarise yourself with the local area where you will be doing your formal training and get to know airfields, landmarks, airspace restrictions etc.
Structured hour building is another cost on the way to getting your licence. Don't go boring holes in the sky, make the most of it and enjoy. It will probably be the only time you have a fixed number of hours to fill in that way.
Dry lease excludes fuel.