Trying to understand and modify Cisco Router RV345

So I just joined a small company and I am the only IT person.  Currently we are running out of IP's on one of our subnet that was setup by non-technical person.  It is a mess but I hope to resolve the issue with some help and guidance.  Here is what we have...

192.168.0.x is setup on Cisco Router
192.168.2.x is setup on another Netgear Router
192.168.3.x is setup on a D-Link Router.

I am still trying to wrap my head around as to why things are done the way it is done.  They have no Windows server or any firewall appliance.  However, they have Comcast and AT&T ISP.  They also have Peplink 20 Balance that has Comcast and AT&T connected with AT&T as a backup

I purchased a SonicWall TZ series.  I have not implemented it yet.  So this is what I need guidance on, as far as my setup

Cloud (AT&T and Comcast) ----->Peplink -----> SonicWall ------> Cisco Router

Then I want to setup VLAN's on Cisco Router for different subnet they have.  Is this possible?  If so, how can I prevent running out of IP's that we are currently facing, especially on 192.168.0.x which connects to all mobile devices, cameras and access points.  

This is a warehouse and they are heavily dependent on mobile devices as this is their prime business.