No; Training Labs are limited time engagements, so once you purchase one, you have the allotted amount of time to complete it, after which the instance is deprovisioned and the cloud resources are deleted.
However, some labs make their content (e.g. instructions, course material) available to users for some time, even after the lab environment has been deleted. You can always go back and review the lab material in these cases.
You can also reach out to a Publisher to ask about repeating their Training Lab.
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