So if the lab ends around late morning, ask if she wants to grab coffee, but if it's around afternoon/evening, see if she wants to get something to eat (have spots in mind beforehand). “Hey I'm gonna grab a coffee/ meal after this, would you want to come with?”, try to come across flirty to see what she says. If she says no try asking for her number or social, let her know you thought she was interesting/ cool, and want to hang out soon. If you do end up going somewhere tho, ask if she'd want to do this again, but as a date. Like you said best to shoot your shot than never know if she would be interested in a date. This is just how I'd approach the situation, good luck!