[Arunava Dey]

I can't update my microsoft lumia 535 with mobile data

[Harrie-S]

Indeed you need wifi for updates.
But there is a workaround but you need a second phone. If you have data on your SIM which you want to ise then pit your SIM in the second phone and start "internet sharing". Then connect your phone to this wifi hotspot. Now you use a "wifi connection".
But be aware that the mobile data you have should be stable otherwise the downloading may fail.

Good luck.