Can I increase the size of my AC compressor with the same refrigerant lines?
You have a refrigerant leak and should probably replace the refrigerant lines regardless. Depending on the type of refrigerant, leaks contribute to ozone depletion and global warming.

A 2.5 ton unit will require a higher airflow rate (typically 350–450 cfm/ton). Your fan motor may or may not be able to be set to a higher speed by moving the jumpers.

With a higher flow rate, your ductwork will induce a higher pressure drop. This means you may not be able to actually achieve the required airflow rate.

A 2.5 ton unit may be oversized and short-cycle more often. This can lead to worse dehumidification performance (your home cools down but stays humid) because moisture condensed into the condensate tray re-evaporates before building up enough to drain.