Prize draws have a different target logic to standard crowdfunding.
For a standard campaign, the target is tied to a specific deliverable. For a prize draw, there's rarely a natural ceiling. The mechanic isn't "we need this amount to do the thing." It's "the more people enter, the more good we can do." Treat your initial target as a milestone to hit and build past, not a ceiling to stop at.
Because donors aren't funding a specific deliverable, they're buying a ticket. Raising the target midway doesn't carry the same risk of appearing to move the goalposts that it does in standard crowdfunding. "We've smashed our target. Let's see how much more we can raise" keeps the energy going rather than closing the story off.
Communicate clearly about what the money funds. Transparency about the destination of funds is what builds the trust that makes people enter in the first place, and come back the following year.
The Talent Fund runs draws at very different scales across the same year: an Ed Sheeran draw raised £163,850 while an Annie Lennox/SISTERS draw raised £25,390. Running multiple draws throughout the year at different scales adds up. You don't need every draw to be the big one. You need a programme of draws that collectively builds to a significant annual total.