Ended up with this on the back tire, went out and could feel the road more than usual.... sealant was up the back of the bike. Got a new tire fitted at the shop so they sorted the sealant as part of that. £8 i didn't think was to bad for labour and £49 for the tire, £4 for the sealant.I'd be tempted to start from fresh and give the tyres and rims a good cleanup.
If you do just top up then get some Stans sealing in a 2oz bottle. The end of the bottle can go into the valve core hole without you needing a syringe. You will also need a valve core remover too ofc.

Do you have a power meter? Do you know it's power your losing and not just speed?
I don't have a power meter, only tracking i have is my garmin watch. I'd love it if it didn't happen mind but just feel sometimes i don't get much into a hill before i'm right in the low gears.
