no, for mordern plan, u cannot use your internet plan without keeping your hotlink account active. u have to reload and keep your hotlink account active so that u can use those internet plan.
The expire date of the internet plan will stay the same , after u reloading your hotlink credit.
for old plan (which has PPU), u still can use your internet plan while ur hotlink account in grance period. But, I'm not sure how many users still stick at those plan, especially 3G is gone in MY.