I live in the same house I have lived for over a decade so my friends have always been local. I moved my job twice so I was spending more time in the week out of the area so I wasn't available in the evenings, despite staying in the same house.
After I while I realised I had lost contact with a lot of my friends. There are only so many times you say no to an invite from someone before they stop inviting you.
So, I live my life with the motto, treat others as you want to be treated. I give my friends time and they give me time back. I make an effort to see how people are with the odd text or phone call and get the same back.
A lot of people I know say that nobody makes an effort with them anymore and it is always the people that have stopped making an effor that are saying it.
Go out of your way to talk to them, invite them to things and get back in the loop. My social life has been a lot busier with people I have barely spoken to in years since I started living like this.