Can a corporation reverse a continuance and come back to being an Ontario corporation?

Yes. Continuance isn't a one-way door. A corporation that previously continued out of Ontario into another jurisdiction can generally apply to continue back into Ontario under the Business Corporations Act, provided Ontario's continuance provisions are satisfied and the corporation's current governing jurisdiction permits it to continue out in the first place. The same underlying legal entity keeps existing throughout; it simply changes which corporate statute governs it, in either direction.

The practical requirements mirror an outbound continuance: shareholder approval by special resolution is typically needed, since it's a fundamental change, along with dissent rights for shareholders who oppose the move. The corporation will also need to re-establish an Ontario registered office and update its structure to comply with Ontario requirements, such as its articles and any director residency or governance rules that differ from wherever it's coming from.

Businesses sometimes reverse a continuance after relocating operations back to Ontario, or after finding that the other jurisdiction's rules didn't suit them as expected. Because both the current and destination jurisdiction's law need to line up to permit the move, confirm both sides before assuming a return continuance is available.