First, check with his vet to make sure there's not an underlining medical reason that doesn't let him hold his bladder for long...veryy important to rule out.
you'll probably get different advice from people. Just choose which sounds best for you and your dog and stick with that one to give it a real chance.
You're dog shouldn't need to go out every 1 1/2 hours if nothing is wrong with him. It also sounds like he's starting to mark which means there are
two separate problems. Has he been neutered? That might help with the marking! It helped my Lhasa greatly but didn't eliminate it completely (granted mine was much older when he was neutered and by that time was a manic marker). The sooner you neuter the better.
If the potty problems aren't medical I would use a crate. I don't know if you already do or whether your dog keeps it clean as you didn't mention that. I would give the dog less roaming privilege in the house until there's a better handle on house training. Some people don't like using crates, I think they speed up the potty training process.
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First step, try to figure out how long
after he eats/drinks he needs to empty his bladder.
Second, figure out with an
empty bladder approx how long he can hold it.
With the info you figured out in mind & working around whatever your daily schedule is you're going to write out a dog schedule and post it by your clock

If you don't work outside of home?..It should look something like this:
7 am ... potty break
Follow how to reward below
7:20 ... water/feed
7:30 .. crate
8:00 - 8:20 ... potty break
8:20 - 9:20... inside playtime/
you MUST commit this time to watch him & only him w/out distraction. Follow how to correct & reward below..
9:20 .. crate
11:30.. potty break
11:50..inside playtime
12:50...crate
----- on and on
-----
----
9:30 .... last water
11:00.. last potty then crate overnight
Leave enough room on your chart so that with each new day you can keep track of any accidents'
when & why. After a couple days you should have a better understanding of what is going on and adjust the chart as needed.
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**If you ever see him circling, sniffing around, walking towards the door or doing anything indoors that cues you in that he might be looking to relieve himself. Take him out asap.
REWARD if he relieves outdoors. Find his favorite treat & only give it to him then, cheer, tell him, "WHAT A GREAT BOY YOU ARE!!!" Give him a few more minutes to see if he's emptied his bladder. Come back and continue following your chart. then go back to schedule
**If when he's he has an accident indoors,
CORRECT him: clap your hands loud and say "No!" The point is to startle him. Walk him out asap. Ignore him outdoors until he relieves himself. Again, REWARD like crazy!!.. give him a few minutes. Then back in following schedule.
Hope this helps.