If we stay at this hotel and buy tickets to Sunway Lagoon, can we exit and reenter multiple times (small kids and need naps/refreshments).
unfortunately no. i hope the resort will allow hotel guests multiple entry.
No you can't - unfortunately they only allow entry once. If you are planning to fully explore the theme park with young kids, you may want to consider buying a two days pass.
Get an answer from Sunway Resort Hotel & Spa staff and past guests.