It's common for salespeople to follow up with long-time prospects every now and then, to see if anything's changed about their situation.
One way top salespeople build rapport with these prospects over time is by writing down specific details they discussed immediately after each call.
Once this information is stored with the lead, it's much easier for salespeople to reintroduce themselves (e.g., "The last time we spoke, you were telling me about a new product you were about to launch. How'd that go?").
The more rapport salespeople build with each prospect, the less awkward the occasional follow-up call becomes.