The best way to increase applications to your syndicate is to have a consistent, high-quality deal flow. When LPs search for syndicates, they often search for syndicates with an active deal or high deal flow.
In addition, when you bring a high-quality deal to the platform, it may be eligible to be sent out to the AngelList LP network via Platform Capital Invites. If your deal qualifies for Platform Capital Invites, you can search for LPs in the AngelList network and send up to 1,000 invites for your deal. You can learn more here.