有今生無來世既英文諺語係?"

The real meaning of 有今生無來世 in English is:
Do treasure everything you own (of your current life).

Indeed, we shouldn't add (of your current life).
Reluctantly, this is just to suit the spirit of your meaning in Chinese.

you only live one

有今生無來世既英文諺語係:

You only live once.