Hi Alan! Your Autopass Card can be topped up to a maximum of $500. You can top up your card in the following ways:

Via NETS

Singapore Bank ATMs (DBS/ POSB/ OCBC/ UOB)

NETS Self-Service Stations

NETS Top-Up Machines located at selected car parks

NETS Sales & Customer Service Centre

Via cash

7-Eleven

Cheers

FairPrice Xpress

Via credit and debit cards (Foreign and Singapore-issued)

For NETS FlashPay card: Download the NETS App from Google Play Store or Apple App Store and register for Auto Top-Up (ATU) service to top up on-the-go. Registration for ATU service is not required for ad-hoc top-up.

General Ticketing Machines (GTMs) at MRT stations

More details can be found here: https://onemotoring.lta.gov.sg/content/onemotoring/home/driving/entering_and_exiting_singapore/autopass-card.html