I have this T-Mobile LTE Hotspot pad and I go through the data fast. The speed goes down to about 150-200kbps after I finish the faster data. Is there anyway that I can improve the speeds without buying more data?
No unless you manage to hack into their server and make them forget how much data you used.
What can you do tho is use ublock origin to not download files bigger than X so that you use less data
Yeah your options are reduce data consumption or get a different plan. If you mention what devices you have there might be some suggestions for reducing data use
Design an app that predicts your internet habits, and caches data according to them, in a predictive manner. Build said app, and install it on your device or a server connected to the hotspot. Then realize what you've created, and sell it for a small fortune.