Suggest you meet up for an hour or two but make it clear you are going elsewhere at a specified time - meeting friends, need an early night for work, babysitting for a mate, whatever.
If you are still enjoying yourself you can 'make a phone call' and cancel prior arrangement.
Or have one of those apps on your phone that ring you at a specified time so you can make excuses and leave if you need to.
A date is merely dipping your toe in. You haven't agreed to go skinny dipping.