OS X Yosemite permanent environement variables
have you tried adding them to your .bash_profile? 

assuming you know how to use the vi editor:


open terminal
enter vi ~/.bash_profile
add one line like the following for each environment variable you need to persist


export PS1='\[\033[34m\]\w\[\e[m\]   '

Save the file. 
Restart your computer. 


The only other thing would be to consider backing up your .bash_profile in case somehow you lose or corrupt it.