Take a slow LFO and use something like Befaco attenuverter to lower it’s level and invert it.
Have the LFO reset at gate release. Add this signal to your pitch CV.
okay, just made it work using Andrew’s suggestion. It didn’t initially occur to me to use the FM input.
This is one of those things that sounds like it ought to be so easy that it would be routine to make work but it’s a little harder than it looks.
Do you want auto slide like in Roland SH1 ?
you need an ADSR with an EOS pulse (End of sustain)
when the EOS is out, trig a secondary AR with inversed scale that modifies the cv IN