diff --git a/guides/developer/preview-projects.mdx b/guides/developer/preview-projects.mdx
index 605c2361..6ac1255e 100644
--- a/guides/developer/preview-projects.mdx
+++ b/guides/developer/preview-projects.mdx
@@ -193,6 +193,23 @@ lightdash preview --name "PR: Add Revenue Metric"
 lightdash preview --name "Long-lived preview" --expires-in 240
 ```
 
+### Refreshing expiration on an existing preview
+
+Re-running `lightdash start-preview` with the same `--name` as an existing preview refreshes its expiration. `expires_at` is recomputed from the moment of the re-run using the same rules as a fresh preview — bounded by the upstream project's default and maximum.
+
+Omitting `--expires-in` on a re-run resets the expiration to the upstream project's default, since a re-run is treated as confirmation that the preview is still in use.
+
+```bash
+# First run: creates the preview and sets expires_at based on the upstream default
+lightdash start-preview --name "ecom-shop-analytics"
+
+# Later re-run without --expires-in: resets expires_at to the upstream default from now
+lightdash start-preview --name "ecom-shop-analytics"
+
+# Re-run with an explicit value: sets expires_at to 72 hours from now (capped at the maximum)
+lightdash start-preview --name "ecom-shop-analytics" --expires-in 72
+```
+
 ## Deleting a Preview Project
 
 Preview projects created using any method can be deleted in the [Lightdash App](/guides/developer/preview-projects#lightdash-app-2).
diff --git a/references/lightdash-cli.mdx b/references/lightdash-cli.mdx
index a1069510..fb17201b 100644
--- a/references/lightdash-cli.mdx
+++ b/references/lightdash-cli.mdx
@@ -391,6 +391,10 @@ All standard [dbt options](#dbt-options) work with `lightdash start-preview`.
   - (default: false)
   - Snowflake only. Disable converting timestamps to UTC. Applied and persisted when creating the preview project. When updating an existing preview, the flag is ignored with a warning and the saved project setting is used instead.
 
+<Info>
+  **Re-running `lightdash start-preview` refreshes the expiration.** If the named preview already exists, `expires_at` is recomputed from the moment of the re-run using the same rules as a fresh preview (bounded by the upstream project's default and maximum). Omitting `--expires-in` on a re-run resets the expiration to the upstream project's default — a re-run is treated as confirmation that the preview is still in use.
+</Info>
+
 
 ### `lightdash stop-preview`